diff --git a/deps/nghttp2/lib/includes/nghttp2/nghttp2.h b/deps/nghttp2/lib/includes/nghttp2/nghttp2.h
index 925a4cbcaf6d6a..313fb23daa7449 100644
--- a/deps/nghttp2/lib/includes/nghttp2/nghttp2.h
+++ b/deps/nghttp2/lib/includes/nghttp2/nghttp2.h
@@ -2648,6 +2648,17 @@ nghttp2_option_set_max_deflate_dynamic_table_size(nghttp2_option *option,
 NGHTTP2_EXTERN void nghttp2_option_set_no_closed_streams(nghttp2_option *option,
                                                          int val);
 
+/**
+ * @function
+ *
+ * This function sets the maximum number of outgoing SETTINGS ACK and
+ * PING ACK frames retained in :type:`nghttp2_session` object.  If
+ * more than those frames are retained, the peer is considered to be
+ * misbehaving and session will be closed.  The default value is 1000.
+ */
+NGHTTP2_EXTERN void nghttp2_option_set_max_outbound_ack(nghttp2_option *option,
+                                                        size_t val);
+
 /**
  * @function
  *
diff --git a/deps/nghttp2/lib/includes/nghttp2/nghttp2ver.h b/deps/nghttp2/lib/includes/nghttp2/nghttp2ver.h
index 210cfaa16ae816..45bb0c9102cb05 100644
--- a/deps/nghttp2/lib/includes/nghttp2/nghttp2ver.h
+++ b/deps/nghttp2/lib/includes/nghttp2/nghttp2ver.h
@@ -29,7 +29,7 @@
  * @macro
  * Version number of the nghttp2 library release
  */
-#define NGHTTP2_VERSION "1.39.1"
+#define NGHTTP2_VERSION "1.39.2"
 
 /**
  * @macro
@@ -37,6 +37,6 @@
  * release. This is a 24 bit number with 8 bits for major number, 8 bits
  * for minor and 8 bits for patch. Version 1.2.3 becomes 0x010203.
  */
-#define NGHTTP2_VERSION_NUM 0x012701
+#define NGHTTP2_VERSION_NUM 0x012702
 
 #endif /* NGHTTP2VER_H */
diff --git a/deps/nghttp2/lib/nghttp2_option.c b/deps/nghttp2/lib/nghttp2_option.c
index 8946d7dd38cfb8..e53f22d367f84a 100644
--- a/deps/nghttp2/lib/nghttp2_option.c
+++ b/deps/nghttp2/lib/nghttp2_option.c
@@ -116,3 +116,8 @@ void nghttp2_option_set_no_closed_streams(nghttp2_option *option, int val) {
   option->opt_set_mask |= NGHTTP2_OPT_NO_CLOSED_STREAMS;
   option->no_closed_streams = val;
 }
+
+void nghttp2_option_set_max_outbound_ack(nghttp2_option *option, size_t val) {
+  option->opt_set_mask |= NGHTTP2_OPT_MAX_OUTBOUND_ACK;
+  option->max_outbound_ack = val;
+}
diff --git a/deps/nghttp2/lib/nghttp2_option.h b/deps/nghttp2/lib/nghttp2_option.h
index 29e72aa321007a..1f740aaa6e364e 100644
--- a/deps/nghttp2/lib/nghttp2_option.h
+++ b/deps/nghttp2/lib/nghttp2_option.h
@@ -66,6 +66,7 @@ typedef enum {
   NGHTTP2_OPT_MAX_SEND_HEADER_BLOCK_LENGTH = 1 << 8,
   NGHTTP2_OPT_MAX_DEFLATE_DYNAMIC_TABLE_SIZE = 1 << 9,
   NGHTTP2_OPT_NO_CLOSED_STREAMS = 1 << 10,
+  NGHTTP2_OPT_MAX_OUTBOUND_ACK = 1 << 11,
 } nghttp2_option_flag;
 
 /**
@@ -80,6 +81,10 @@ struct nghttp2_option {
    * NGHTTP2_OPT_MAX_DEFLATE_DYNAMIC_TABLE_SIZE
    */
   size_t max_deflate_dynamic_table_size;
+  /**
+   * NGHTTP2_OPT_MAX_OUTBOUND_ACK
+   */
+  size_t max_outbound_ack;
   /**
    * Bitwise OR of nghttp2_option_flag to determine that which fields
    * are specified.
diff --git a/deps/nghttp2/lib/nghttp2_session.c b/deps/nghttp2/lib/nghttp2_session.c
index 33d987667edaf5..3420cfa2f1c653 100644
--- a/deps/nghttp2/lib/nghttp2_session.c
+++ b/deps/nghttp2/lib/nghttp2_session.c
@@ -457,6 +457,7 @@ static int session_new(nghttp2_session **session_ptr,
   (*session_ptr)->remote_settings.max_concurrent_streams = 100;
 
   (*session_ptr)->max_send_header_block_length = NGHTTP2_MAX_HEADERSLEN;
+  (*session_ptr)->max_outbound_ack = NGHTTP2_DEFAULT_MAX_OBQ_FLOOD_ITEM;
 
   if (option) {
     if ((option->opt_set_mask & NGHTTP2_OPT_NO_AUTO_WINDOW_UPDATE) &&
@@ -516,6 +517,10 @@ static int session_new(nghttp2_session **session_ptr,
         option->no_closed_streams) {
       (*session_ptr)->opt_flags |= NGHTTP2_OPTMASK_NO_CLOSED_STREAMS;
     }
+
+    if (option->opt_set_mask & NGHTTP2_OPT_MAX_OUTBOUND_ACK) {
+      (*session_ptr)->max_outbound_ack = option->max_outbound_ack;
+    }
   }
 
   rv = nghttp2_hd_deflate_init2(&(*session_ptr)->hd_deflater,
@@ -6857,7 +6862,7 @@ int nghttp2_session_add_ping(nghttp2_session *session, uint8_t flags,
   mem = &session->mem;
 
   if ((flags & NGHTTP2_FLAG_ACK) &&
-      session->obq_flood_counter_ >= NGHTTP2_MAX_OBQ_FLOOD_ITEM) {
+      session->obq_flood_counter_ >= session->max_outbound_ack) {
     return NGHTTP2_ERR_FLOODED;
   }
 
@@ -7002,7 +7007,7 @@ int nghttp2_session_add_settings(nghttp2_session *session, uint8_t flags,
       return NGHTTP2_ERR_INVALID_ARGUMENT;
     }
 
-    if (session->obq_flood_counter_ >= NGHTTP2_MAX_OBQ_FLOOD_ITEM) {
+    if (session->obq_flood_counter_ >= session->max_outbound_ack) {
       return NGHTTP2_ERR_FLOODED;
     }
   }
diff --git a/deps/nghttp2/lib/nghttp2_session.h b/deps/nghttp2/lib/nghttp2_session.h
index bd7a5b35817599..90ead9c0395b4f 100644
--- a/deps/nghttp2/lib/nghttp2_session.h
+++ b/deps/nghttp2/lib/nghttp2_session.h
@@ -97,7 +97,7 @@ typedef struct {
    response frames are stacked up, which leads to memory exhaustion.
    The value selected here is arbitrary, but safe value and if we have
    these frames in this number, it is considered suspicious. */
-#define NGHTTP2_MAX_OBQ_FLOOD_ITEM 10000
+#define NGHTTP2_DEFAULT_MAX_OBQ_FLOOD_ITEM 1000
 
 /* The default value of maximum number of concurrent streams. */
 #define NGHTTP2_DEFAULT_MAX_CONCURRENT_STREAMS 0xffffffffu
@@ -258,8 +258,12 @@ struct nghttp2_session {
   size_t num_idle_streams;
   /* The number of bytes allocated for nvbuf */
   size_t nvbuflen;
-  /* Counter for detecting flooding in outbound queue */
+  /* Counter for detecting flooding in outbound queue.  If it exceeds
+     max_outbound_ack, session will be closed. */
   size_t obq_flood_counter_;
+  /* The maximum number of outgoing SETTINGS ACK and PING ACK in
+     outbound queue. */
+  size_t max_outbound_ack;
   /* The maximum length of header block to send.  Calculated by the
      same way as nghttp2_hd_deflate_bound() does. */
   size_t max_send_header_block_length;
diff --git a/lib/internal/http2/core.js b/lib/internal/http2/core.js
index fca37ae2b0812a..69666bb6ba5853 100644
--- a/lib/internal/http2/core.js
+++ b/lib/internal/http2/core.js
@@ -138,6 +138,26 @@ const { StreamPipe } = internalBinding('stream_pipe');
 const { _connectionListener: httpConnectionListener } = http;
 const debug = require('internal/util/debuglog').debuglog('http2');
 
+// TODO(addaleax): See if this can be made more efficient by figuring out
+// whether debugging is enabled before we perform any further steps. Currently,
+// this seems pretty fast, though.
+function debugStream(id, sessionType, message, ...args) {
+  debug('Http2Stream %s [Http2Session %s]: ' + message,
+        id, sessionName(sessionType), ...args);
+}
+
+function debugStreamObj(stream, message, ...args) {
+  debugStream(stream[kID], stream[kSession][kType], ...args);
+}
+
+function debugSession(sessionType, message, ...args) {
+  debug('Http2Session %s: ' + message, sessionName(sessionType), ...args);
+}
+
+function debugSessionObj(session, message, ...args) {
+  debugSession(session[kType], message, ...args);
+}
+
 const kMaxFrameSize = (2 ** 24) - 1;
 const kMaxInt = (2 ** 32) - 1;
 const kMaxStreams = (2 ** 31) - 1;
@@ -157,6 +177,7 @@ const kID = Symbol('id');
 const kInit = Symbol('init');
 const kInfoHeaders = Symbol('sent-info-headers');
 const kLocalSettings = Symbol('local-settings');
+const kNativeFields = Symbol('kNativeFields');
 const kOptions = Symbol('options');
 const kOwner = owner_symbol;
 const kOrigin = Symbol('origin');
@@ -176,7 +197,15 @@ const {
   paddingBuffer,
   PADDING_BUF_FRAME_LENGTH,
   PADDING_BUF_MAX_PAYLOAD_LENGTH,
-  PADDING_BUF_RETURN_VALUE
+  PADDING_BUF_RETURN_VALUE,
+  kBitfield,
+  kSessionPriorityListenerCount,
+  kSessionFrameErrorListenerCount,
+  kSessionUint8FieldCount,
+  kSessionHasRemoteSettingsListeners,
+  kSessionRemoteSettingsIsUpToDate,
+  kSessionHasPingListeners,
+  kSessionHasAltsvcListeners,
 } = binding;
 
 const {
@@ -256,8 +285,7 @@ function onSessionHeaders(handle, id, cat, flags, headers) {
 
   const type = session[kType];
   session[kUpdateTimer]();
-  debug(`Http2Stream ${id} [Http2Session ` +
-        `${sessionName(type)}]: headers received`);
+  debugStream(id, type, 'headers received');
   const streams = session[kState].streams;
 
   const endOfStream = !!(flags & NGHTTP2_FLAG_END_STREAM);
@@ -317,8 +345,7 @@ function onSessionHeaders(handle, id, cat, flags, headers) {
       const originSet = session[kState].originSet = initOriginSet(session);
       originSet.delete(stream[kOrigin]);
     }
-    debug(`Http2Stream ${id} [Http2Session ` +
-          `${sessionName(type)}]: emitting stream '${event}' event`);
+    debugStream(id, type, "emitting stream '%s' event", event);
     process.nextTick(emit, stream, event, obj, flags, headers);
   }
   if (endOfStream) {
@@ -354,12 +381,82 @@ function submitRstStream(code) {
   }
 }
 
+// Keep track of the number/presence of JS event listeners. Knowing that there
+// are no listeners allows the C++ code to skip calling into JS for an event.
+function sessionListenerAdded(name) {
+  switch (name) {
+    case 'ping':
+      this[kNativeFields][kBitfield] |= 1 << kSessionHasPingListeners;
+      break;
+    case 'altsvc':
+      this[kNativeFields][kBitfield] |= 1 << kSessionHasAltsvcListeners;
+      break;
+    case 'remoteSettings':
+      this[kNativeFields][kBitfield] |= 1 << kSessionHasRemoteSettingsListeners;
+      break;
+    case 'priority':
+      this[kNativeFields][kSessionPriorityListenerCount]++;
+      break;
+    case 'frameError':
+      this[kNativeFields][kSessionFrameErrorListenerCount]++;
+      break;
+  }
+}
+
+function sessionListenerRemoved(name) {
+  switch (name) {
+    case 'ping':
+      if (this.listenerCount(name) > 0) return;
+      this[kNativeFields][kBitfield] &= ~(1 << kSessionHasPingListeners);
+      break;
+    case 'altsvc':
+      if (this.listenerCount(name) > 0) return;
+      this[kNativeFields][kBitfield] &= ~(1 << kSessionHasAltsvcListeners);
+      break;
+    case 'remoteSettings':
+      if (this.listenerCount(name) > 0) return;
+      this[kNativeFields][kBitfield] &=
+          ~(1 << kSessionHasRemoteSettingsListeners);
+      break;
+    case 'priority':
+      this[kNativeFields][kSessionPriorityListenerCount]--;
+      break;
+    case 'frameError':
+      this[kNativeFields][kSessionFrameErrorListenerCount]--;
+      break;
+  }
+}
+
+// Also keep track of listeners for the Http2Stream instances, as some events
+// are emitted on those objects.
+function streamListenerAdded(name) {
+  switch (name) {
+    case 'priority':
+      this[kSession][kNativeFields][kSessionPriorityListenerCount]++;
+      break;
+    case 'frameError':
+      this[kSession][kNativeFields][kSessionFrameErrorListenerCount]++;
+      break;
+  }
+}
+
+function streamListenerRemoved(name) {
+  switch (name) {
+    case 'priority':
+      this[kSession][kNativeFields][kSessionPriorityListenerCount]--;
+      break;
+    case 'frameError':
+      this[kSession][kNativeFields][kSessionFrameErrorListenerCount]--;
+      break;
+  }
+}
+
 function onPing(payload) {
   const session = this[kOwner];
   if (session.destroyed)
     return;
   session[kUpdateTimer]();
-  debug(`Http2Session ${sessionName(session[kType])}: new ping received`);
+  debugSessionObj(session, 'new ping received');
   session.emit('ping', payload);
 }
 
@@ -374,8 +471,7 @@ function onStreamClose(code) {
   if (!stream || stream.destroyed)
     return false;
 
-  debug(`Http2Stream ${stream[kID]} [Http2Session ` +
-        `${sessionName(stream[kSession][kType])}]: closed with code ${code}`);
+  debugStreamObj(stream, 'closed with code %d', code);
 
   if (!stream.closed)
     closeStream(stream, code, kNoRstStream);
@@ -412,8 +508,7 @@ function onSettings() {
   if (session.destroyed)
     return;
   session[kUpdateTimer]();
-  debug(`Http2Session ${sessionName(session[kType])}: new settings received`);
-  session[kRemoteSettings] = undefined;
+  debugSessionObj(session, 'new settings received');
   session.emit('remoteSettings', session.remoteSettings);
 }
 
@@ -424,9 +519,9 @@ function onPriority(id, parent, weight, exclusive) {
   const session = this[kOwner];
   if (session.destroyed)
     return;
-  debug(`Http2Stream ${id} [Http2Session ` +
-        `${sessionName(session[kType])}]: priority [parent: ${parent}, ` +
-        `weight: ${weight}, exclusive: ${exclusive}]`);
+  debugStream(id, session[kType],
+              'priority [parent: %d, weight: %d, exclusive: %s]',
+              parent, weight, exclusive);
   const emitter = session[kState].streams.get(id) || session;
   if (!emitter.destroyed) {
     emitter[kUpdateTimer]();
@@ -440,8 +535,8 @@ function onFrameError(id, type, code) {
   const session = this[kOwner];
   if (session.destroyed)
     return;
-  debug(`Http2Session ${sessionName(session[kType])}: error sending frame ` +
-        `type ${type} on stream ${id}, code: ${code}`);
+  debugSessionObj(session, 'error sending frame type %d on stream %d, code: %d',
+                  type, id, code);
   const emitter = session[kState].streams.get(id) || session;
   emitter[kUpdateTimer]();
   emitter.emit('frameError', type, code, id);
@@ -451,8 +546,8 @@ function onAltSvc(stream, origin, alt) {
   const session = this[kOwner];
   if (session.destroyed)
     return;
-  debug(`Http2Session ${sessionName(session[kType])}: altsvc received: ` +
-        `stream: ${stream}, origin: ${origin}, alt: ${alt}`);
+  debugSessionObj(session, 'altsvc received: stream: %d, origin: %s, alt: %s',
+                  stream, origin, alt);
   session[kUpdateTimer]();
   session.emit('altsvc', alt, origin, stream);
 }
@@ -479,8 +574,7 @@ function onOrigin(origins) {
   const session = this[kOwner];
   if (session.destroyed)
     return;
-  debug('Http2Session %s: origin received: %j',
-        sessionName(session[kType]), origins);
+  debugSessionObj(session, 'origin received: %j', origins);
   session[kUpdateTimer]();
   if (!session.encrypted || session.destroyed)
     return undefined;
@@ -500,8 +594,8 @@ function onGoawayData(code, lastStreamID, buf) {
   const session = this[kOwner];
   if (session.destroyed)
     return;
-  debug(`Http2Session ${sessionName(session[kType])}: goaway ${code} ` +
-        `received [last stream id: ${lastStreamID}]`);
+  debugSessionObj(session, 'goaway %d received [last stream id: %d]',
+                  code, lastStreamID);
 
   const state = session[kState];
   state.goawayCode = code;
@@ -556,8 +650,7 @@ function requestOnConnect(headers, options) {
     return;
   }
 
-  debug(`Http2Session ${sessionName(session[kType])}: connected, ` +
-        'initializing request');
+  debugSessionObj(session, 'connected, initializing request');
 
   let streamOptions = 0;
   if (options.endStream)
@@ -646,13 +739,13 @@ function settingsCallback(cb, ack, duration) {
   this[kState].pendingAck--;
   this[kLocalSettings] = undefined;
   if (ack) {
-    debug(`Http2Session ${sessionName(this[kType])}: settings received`);
+    debugSessionObj(this, 'settings received');
     const settings = this.localSettings;
     if (typeof cb === 'function')
       cb(null, settings, duration);
     this.emit('localSettings', settings);
   } else {
-    debug(`Http2Session ${sessionName(this[kType])}: settings canceled`);
+    debugSessionObj(this, 'settings canceled');
     if (typeof cb === 'function')
       cb(new ERR_HTTP2_SETTINGS_CANCEL());
   }
@@ -662,7 +755,7 @@ function settingsCallback(cb, ack, duration) {
 function submitSettings(settings, callback) {
   if (this.destroyed)
     return;
-  debug(`Http2Session ${sessionName(this[kType])}: submitting settings`);
+  debugSessionObj(this, 'submitting settings');
   this[kUpdateTimer]();
   updateSettingsBuffer(settings);
   if (!this[kHandle].settings(settingsCallback.bind(this, callback))) {
@@ -696,7 +789,7 @@ function submitPriority(options) {
 function submitGoaway(code, lastStreamID, opaqueData) {
   if (this.destroyed)
     return;
-  debug(`Http2Session ${sessionName(this[kType])}: submitting goaway`);
+  debugSessionObj(this, 'submitting goaway');
   this[kUpdateTimer]();
   this[kHandle].goaway(code, lastStreamID, opaqueData);
 }
@@ -827,7 +920,7 @@ function setupHandle(socket, type, options) {
          'Internal HTTP/2 Failure. The socket is not connected. Please ' +
          'report this as a bug in Node.js');
 
-  debug(`Http2Session ${sessionName(type)}: setting up session handle`);
+  debugSession(type, 'setting up session handle');
   this[kState].flags |= SESSION_FLAGS_READY;
 
   updateOptionsBuffer(options);
@@ -839,6 +932,10 @@ function setupHandle(socket, type, options) {
   handle.consume(socket._handle);
 
   this[kHandle] = handle;
+  if (this[kNativeFields])
+    handle.fields.set(this[kNativeFields]);
+  else
+    this[kNativeFields] = handle.fields;
 
   if (socket.encrypted) {
     this[kAlpnProtocol] = socket.alpnProtocol;
@@ -880,6 +977,7 @@ function finishSessionDestroy(session, error) {
   session[kProxySocket] = undefined;
   session[kSocket] = undefined;
   session[kHandle] = undefined;
+  session[kNativeFields] = new Uint8Array(kSessionUint8FieldCount);
   socket[kSession] = undefined;
   socket[kServer] = undefined;
 
@@ -959,6 +1057,7 @@ class Http2Session extends EventEmitter {
     this[kProxySocket] = null;
     this[kSocket] = socket;
     this[kTimeout] = null;
+    this[kHandle] = undefined;
 
     // Do not use nagle's algorithm
     if (typeof socket.setNoDelay === 'function')
@@ -983,7 +1082,12 @@ class Http2Session extends EventEmitter {
       setupFn();
     }
 
-    debug(`Http2Session ${sessionName(type)}: created`);
+    if (!this[kNativeFields])
+      this[kNativeFields] = new Uint8Array(kSessionUint8FieldCount);
+    this.on('newListener', sessionListenerAdded);
+    this.on('removeListener', sessionListenerRemoved);
+
+    debugSession(type, 'created');
   }
 
   // Returns undefined if the socket is not yet connected, true if the
@@ -1140,13 +1244,18 @@ class Http2Session extends EventEmitter {
 
   // The settings currently in effect for the remote peer.
   get remoteSettings() {
-    const settings = this[kRemoteSettings];
-    if (settings !== undefined)
-      return settings;
+    if (this[kNativeFields][kBitfield] &
+        (1 << kSessionRemoteSettingsIsUpToDate)) {
+      const settings = this[kRemoteSettings];
+      if (settings !== undefined) {
+        return settings;
+      }
+    }
 
     if (this.destroyed || this.connecting)
       return {};
 
+    this[kNativeFields][kBitfield] |= (1 << kSessionRemoteSettingsIsUpToDate);
     return this[kRemoteSettings] = getSettings(this[kHandle], true); // Remote
   }
 
@@ -1159,7 +1268,7 @@ class Http2Session extends EventEmitter {
 
     if (callback && typeof callback !== 'function')
       throw new ERR_INVALID_CALLBACK(callback);
-    debug(`Http2Session ${sessionName(this[kType])}: sending settings`);
+    debugSessionObj(this, 'sending settings');
 
     this[kState].pendingAck++;
 
@@ -1200,7 +1309,7 @@ class Http2Session extends EventEmitter {
   destroy(error = NGHTTP2_NO_ERROR, code) {
     if (this.destroyed)
       return;
-    debug(`Http2Session ${sessionName(this[kType])}: destroying`);
+    debugSessionObj(this, 'destroying');
 
     if (typeof error === 'number') {
       code = error;
@@ -1257,7 +1366,7 @@ class Http2Session extends EventEmitter {
   close(callback) {
     if (this.closed || this.destroyed)
       return;
-    debug(`Http2Session ${sessionName(this[kType])}: marking session closed`);
+    debugSessionObj(this, 'marking session closed');
     this[kState].flags |= SESSION_FLAGS_CLOSED;
     if (typeof callback === 'function')
       this.once('close', callback);
@@ -1325,6 +1434,12 @@ class ServerHttp2Session extends Http2Session {
   constructor(options, socket, server) {
     super(NGHTTP2_SESSION_SERVER, options, socket);
     this[kServer] = server;
+    // This is a bit inaccurate because it does not reflect changes to
+    // number of listeners made after the session was created. This should
+    // not be an issue in practice. Additionally, the 'priority' event on
+    // server instances (or any other object) is fully undocumented.
+    this[kNativeFields][kSessionPriorityListenerCount] =
+      server.listenerCount('priority');
   }
 
   get server() {
@@ -1428,7 +1543,7 @@ class ClientHttp2Session extends Http2Session {
   // Submits a new HTTP2 request to the connected peer. Returns the
   // associated Http2Stream instance.
   request(headers, options) {
-    debug(`Http2Session ${sessionName(this[kType])}: initiating request`);
+    debugSessionObj(this, 'initiating request');
 
     if (this.destroyed)
       throw new ERR_HTTP2_INVALID_SESSION();
@@ -1637,6 +1752,9 @@ class Http2Stream extends Duplex {
     this[kProxySocket] = null;
 
     this.on('pause', streamOnPause);
+
+    this.on('newListener', streamListenerAdded);
+    this.on('removeListener', streamListenerRemoved);
   }
 
   [kUpdateTimer]() {
@@ -1828,8 +1946,7 @@ class Http2Stream extends Duplex {
     if (this.pending) {
       this.once('ready', () => this._final(cb));
     } else if (handle !== undefined) {
-      debug(`Http2Stream ${this[kID]} [Http2Session ` +
-            `${sessionName(this[kSession][kType])}]: _final shutting down`);
+      debugStreamObj(this, '_final shutting down');
       const req = new ShutdownWrap();
       req.oncomplete = afterShutdown;
       req.callback = cb;
@@ -1888,9 +2005,7 @@ class Http2Stream extends Duplex {
     assertIsObject(headers, 'headers');
     headers = Object.assign(Object.create(null), headers);
 
-    const session = this[kSession];
-    debug(`Http2Stream ${this[kID]} [Http2Session ` +
-    `${sessionName(session[kType])}]: sending trailers`);
+    debugStreamObj(this, 'sending trailers');
 
     this[kUpdateTimer]();
 
@@ -1943,8 +2058,7 @@ class Http2Stream extends Duplex {
     const handle = this[kHandle];
     const id = this[kID];
 
-    debug(`Http2Stream ${this[kID] || '<pending>'} [Http2Session ` +
-          `${sessionName(session[kType])}]: destroying stream`);
+    debugStream(this[kID] || 'pending', session[kType], 'destroying stream');
 
     const state = this[kState];
     const sessionCode = session[kState].goawayCode ||
@@ -2270,8 +2384,7 @@ class ServerHttp2Stream extends Http2Stream {
 
     const session = this[kSession];
 
-    debug(`Http2Stream ${this[kID]} [Http2Session ` +
-          `${sessionName(session[kType])}]: initiating push stream`);
+    debugStreamObj(this, 'initiating push stream');
 
     this[kUpdateTimer]();
 
@@ -2351,9 +2464,7 @@ class ServerHttp2Stream extends Http2Stream {
     assertIsObject(options, 'options');
     options = { ...options };
 
-    const session = this[kSession];
-    debug(`Http2Stream ${this[kID]} [Http2Session ` +
-          `${sessionName(session[kType])}]: initiating response`);
+    debugStreamObj(this, 'initiating response');
     this[kUpdateTimer]();
 
     options.endStream = !!options.endStream;
@@ -2426,8 +2537,7 @@ class ServerHttp2Stream extends Http2Stream {
 
     validateNumber(fd, 'fd');
 
-    debug(`Http2Stream ${this[kID]} [Http2Session ` +
-          `${sessionName(session[kType])}]: initiating response from fd`);
+    debugStreamObj(this, 'initiating response from fd');
     this[kUpdateTimer]();
     this.ownsFd = false;
 
@@ -2488,8 +2598,7 @@ class ServerHttp2Stream extends Http2Stream {
     }
 
     const session = this[kSession];
-    debug(`Http2Stream ${this[kID]} [Http2Session ` +
-          `${sessionName(session[kType])}]: initiating response from file`);
+    debugStreamObj(this, 'initiating response from file');
     this[kUpdateTimer]();
     this.ownsFd = true;
 
@@ -2523,9 +2632,7 @@ class ServerHttp2Stream extends Http2Stream {
     assertIsObject(headers, 'headers');
     headers = Object.assign(Object.create(null), headers);
 
-    const session = this[kSession];
-    debug(`Http2Stream ${this[kID]} [Http2Session ` +
-    `${sessionName(session[kType])}]: sending additional headers`);
+    debugStreamObj(this, 'sending additional headers');
 
     if (headers[HTTP2_HEADER_STATUS] != null) {
       const statusCode = headers[HTTP2_HEADER_STATUS] |= 0;
@@ -2586,8 +2693,7 @@ function socketOnError(error) {
     // we can do and the other side is fully within its rights to do so.
     if (error.code === 'ECONNRESET' && session[kState].goawayCode !== null)
       return session.destroy();
-    debug(`Http2Session ${sessionName(session[kType])}: socket error [` +
-          `${error.message}]`);
+    debugSessionObj(this, 'socket error [%s]', error.message);
     session.destroy(error);
   }
 }
@@ -2605,7 +2711,7 @@ function sessionOnPriority(stream, parent, weight, exclusive) {
 }
 
 function sessionOnError(error) {
-  if (this[kServer])
+  if (this[kServer] !== undefined)
     this[kServer].emit('sessionError', error, this);
 }
 
@@ -2632,7 +2738,8 @@ function connectionListener(socket) {
       return httpConnectionListener.call(this, socket);
     }
     // Let event handler deal with the socket
-    debug(`Unknown protocol from ${socket.remoteAddress}:${socket.remotePort}`);
+    debug('Unknown protocol from %s:%s',
+          socket.remoteAddress, socket.remotePort);
     if (!this.emit('unknownProtocol', socket)) {
       // We don't know what to do, so let's just tell the other side what's
       // going on in a format that they *might* understand.
@@ -2653,8 +2760,10 @@ function connectionListener(socket) {
   const session = new ServerHttp2Session(options, socket, this);
 
   session.on('stream', sessionOnStream);
-  session.on('priority', sessionOnPriority);
   session.on('error', sessionOnError);
+  // Don't count our own internal listener.
+  session.on('priority', sessionOnPriority);
+  session[kNativeFields][kSessionPriorityListenerCount]--;
 
   if (this.timeout)
     session.setTimeout(this.timeout, sessionOnTimeout);
@@ -2757,7 +2866,7 @@ function setupCompat(ev) {
 function socketOnClose() {
   const session = this[kSession];
   if (session !== undefined) {
-    debug(`Http2Session ${sessionName(session[kType])}: socket closed`);
+    debugSessionObj(session, 'socket closed');
     const err = session.connecting ? new ERR_SOCKET_CLOSED() : null;
     const state = session[kState];
     state.streams.forEach((stream) => stream.close(NGHTTP2_CANCEL));
diff --git a/src/env.h b/src/env.h
index ada3d4f9d8d860..9a0f98e121b380 100644
--- a/src/env.h
+++ b/src/env.h
@@ -230,6 +230,7 @@ constexpr size_t kFsStatsBufferLength =
   V(family_string, "family")                                                   \
   V(fatal_exception_string, "_fatalException")                                 \
   V(fd_string, "fd")                                                           \
+  V(fields_string, "fields")                                                   \
   V(file_string, "file")                                                       \
   V(fingerprint256_string, "fingerprint256")                                   \
   V(fingerprint_string, "fingerprint")                                         \
diff --git a/src/node_http2.cc b/src/node_http2.cc
index 9d6c37373ff487..8cb1158b559dec 100644
--- a/src/node_http2.cc
+++ b/src/node_http2.cc
@@ -6,6 +6,7 @@
 #include "node_http2.h"
 #include "node_http2_state.h"
 #include "node_perf.h"
+#include "node_revert.h"
 #include "util-inl.h"
 
 #include <algorithm>
@@ -25,6 +26,7 @@ using v8::ObjectTemplate;
 using v8::String;
 using v8::Uint32;
 using v8::Uint32Array;
+using v8::Uint8Array;
 using v8::Undefined;
 
 using node::performance::PerformanceEntry;
@@ -149,6 +151,9 @@ Http2Options::Http2Options(Environment* env, nghttp2_session_type type) {
         buffer[IDX_OPTIONS_PEER_MAX_CONCURRENT_STREAMS]);
   }
 
+  if (IsReverted(SECURITY_REVERT_CVE_2019_9512))
+    nghttp2_option_set_max_outbound_ack(options_, 10000);
+
   // The padding strategy sets the mechanism by which we determine how much
   // additional frame padding to apply to DATA and HEADERS frames. Currently
   // this is set on a per-session basis, but eventually we may switch to
@@ -637,8 +642,17 @@ Http2Session::Http2Session(Environment* env,
   // fails.
   CHECK_EQ(fn(&session_, callbacks, this, *opts, *allocator_info), 0);
 
-  outgoing_storage_.reserve(4096);
+  outgoing_storage_.reserve(1024);
   outgoing_buffers_.reserve(32);
+
+  {
+    // Make the js_fields_ property accessible to JS land.
+    Local<ArrayBuffer> ab =
+        ArrayBuffer::New(env->isolate(), js_fields_, kSessionUint8FieldCount);
+    Local<Uint8Array> uint8_arr =
+        Uint8Array::New(ab, 0, kSessionUint8FieldCount);
+    USE(wrap->Set(env->context(), env->fields_string(), uint8_arr));
+  }
 }
 
 Http2Session::~Http2Session() {
@@ -857,31 +871,51 @@ ssize_t Http2Session::OnCallbackPadding(size_t frameLen,
 // various callback functions. Each of these will typically result in a call
 // out to JavaScript so this particular function is rather hot and can be
 // quite expensive. This is a potential performance optimization target later.
-ssize_t Http2Session::Write(const uv_buf_t* bufs, size_t nbufs) {
-  size_t total = 0;
-  // Note that nghttp2_session_mem_recv is a synchronous operation that
-  // will trigger a number of other callbacks. Those will, in turn have
+ssize_t Http2Session::ConsumeHTTP2Data() {
+  CHECK_NOT_NULL(stream_buf_.base);
+  CHECK_LT(stream_buf_offset_, stream_buf_.len);
+  size_t read_len = stream_buf_.len - stream_buf_offset_;
+
   // multiple side effects.
-  for (size_t n = 0; n < nbufs; n++) {
-    Debug(this, "receiving %d bytes [wants data? %d]",
-          bufs[n].len,
-          nghttp2_session_want_read(session_));
-    ssize_t ret =
-      nghttp2_session_mem_recv(session_,
-                               reinterpret_cast<uint8_t*>(bufs[n].base),
-                               bufs[n].len);
-    CHECK_NE(ret, NGHTTP2_ERR_NOMEM);
-
-    if (ret < 0)
-      return ret;
+  Debug(this, "receiving %d bytes [wants data? %d]",
+        read_len,
+        nghttp2_session_want_read(session_));
+  flags_ &= ~SESSION_STATE_NGHTTP2_RECV_PAUSED;
+  ssize_t ret =
+    nghttp2_session_mem_recv(session_,
+                             reinterpret_cast<uint8_t*>(stream_buf_.base) +
+                                 stream_buf_offset_,
+                             read_len);
+  CHECK_NE(ret, NGHTTP2_ERR_NOMEM);
+
+  if (flags_ & SESSION_STATE_NGHTTP2_RECV_PAUSED) {
+    CHECK_NE(flags_ & SESSION_STATE_READING_STOPPED, 0);
 
-    total += ret;
+    CHECK_GT(ret, 0);
+    CHECK_LE(static_cast<size_t>(ret), read_len);
+
+    if (static_cast<size_t>(ret) < read_len) {
+      // Mark the remainder of the data as available for later consumption.
+      stream_buf_offset_ += ret;
+      return ret;
+    }
   }
+
+  // We are done processing the current input chunk.
+  DecrementCurrentSessionMemory(stream_buf_.len);
+  stream_buf_offset_ = 0;
+  stream_buf_ab_.Reset();
+  stream_buf_allocation_.clear();
+  stream_buf_ = uv_buf_init(nullptr, 0);
+
+  if (ret < 0)
+    return ret;
+
   // Send any data that was queued up while processing the received data.
   if (!IsDestroyed()) {
     SendPendingData();
   }
-  return total;
+  return ret;
 }
 
 
@@ -911,11 +945,17 @@ int Http2Session::OnBeginHeadersCallback(nghttp2_session* handle,
     if (UNLIKELY(!session->CanAddStream() ||
                  Http2Stream::New(session, id, frame->headers.cat) ==
                      nullptr)) {
+      if (session->rejected_stream_count_++ > 100 &&
+          !IsReverted(SECURITY_REVERT_CVE_2019_9514)) {
+        return NGHTTP2_ERR_CALLBACK_FAILURE;
+      }
       // Too many concurrent streams being opened
       nghttp2_submit_rst_stream(**session, NGHTTP2_FLAG_NONE, id,
                                 NGHTTP2_ENHANCE_YOUR_CALM);
       return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
     }
+
+    session->rejected_stream_count_ = 0;
   } else if (!stream->IsDestroyed()) {
     stream->StartHeaders(frame->headers.cat);
   }
@@ -962,8 +1002,7 @@ int Http2Session::OnFrameReceive(nghttp2_session* handle,
         frame->hd.type);
   switch (frame->hd.type) {
     case NGHTTP2_DATA:
-      session->HandleDataFrame(frame);
-      break;
+      return session->HandleDataFrame(frame);
     case NGHTTP2_PUSH_PROMISE:
       // Intentional fall-through, handled just like headers frames
     case NGHTTP2_HEADERS:
@@ -1000,6 +1039,10 @@ int Http2Session::OnInvalidFrame(nghttp2_session* handle,
   Http2Session* session = static_cast<Http2Session*>(user_data);
 
   Debug(session, "invalid frame received, code: %d", lib_error_code);
+  if (session->invalid_frame_count_++ > 1000 &&
+      !IsReverted(SECURITY_REVERT_CVE_2019_9514)) {
+    return 1;
+  }
 
   // If the error is fatal or if error code is ERR_STREAM_CLOSED... emit error
   if (nghttp2_is_fatal(lib_error_code) ||
@@ -1033,7 +1076,8 @@ int Http2Session::OnFrameNotSent(nghttp2_session* handle,
   // Do not report if the frame was not sent due to the session closing
   if (error_code == NGHTTP2_ERR_SESSION_CLOSING ||
       error_code == NGHTTP2_ERR_STREAM_CLOSED ||
-      error_code == NGHTTP2_ERR_STREAM_CLOSING) {
+      error_code == NGHTTP2_ERR_STREAM_CLOSING ||
+      session->js_fields_[kSessionFrameErrorListenerCount] == 0) {
     return 0;
   }
 
@@ -1173,8 +1217,18 @@ int Http2Session::OnDataChunkReceived(nghttp2_session* handle,
       nghttp2_session_consume_stream(handle, id, avail);
     else
       stream->inbound_consumed_data_while_paused_ += avail;
+
+    // If we have a gathered a lot of data for output, try sending it now.
+    if (session->outgoing_length_ > 4096) session->SendPendingData();
   } while (len != 0);
 
+  // If we are currently waiting for a write operation to finish, we should
+  // tell nghttp2 that we want to wait before we process more input data.
+  if (session->flags_ & SESSION_STATE_WRITE_IN_PROGRESS) {
+    session->flags_ |= SESSION_STATE_NGHTTP2_RECV_PAUSED;
+    return NGHTTP2_ERR_PAUSE;
+  }
+
   return 0;
 }
 
@@ -1248,7 +1302,13 @@ void Http2StreamListener::OnStreamRead(ssize_t nread, const uv_buf_t& buf) {
     return;
   }
 
-  CHECK(!session->stream_buf_ab_.IsEmpty());
+  Local<ArrayBuffer> ab;
+  if (session->stream_buf_ab_.IsEmpty()) {
+    ab = session->stream_buf_allocation_.ToArrayBuffer();
+    session->stream_buf_ab_.Reset(env->isolate(), ab);
+  } else {
+    ab = PersistentToLocal::Strong(session->stream_buf_ab_);
+  }
 
   // There is a single large array buffer for the entire data read from the
   // network; create a slice of that array buffer and emit it as the
@@ -1256,10 +1316,11 @@ void Http2StreamListener::OnStreamRead(ssize_t nread, const uv_buf_t& buf) {
   size_t offset = buf.base - session->stream_buf_.base;
 
   // Verify that the data offset is inside the current read buffer.
+  CHECK_GE(offset, session->stream_buf_offset_);
   CHECK_LE(offset, session->stream_buf_.len);
   CHECK_LE(offset + buf.len, session->stream_buf_.len);
 
-  stream->CallJSOnreadMethod(nread, session->stream_buf_ab_, offset);
+  stream->CallJSOnreadMethod(nread, ab, offset);
 }
 
 
@@ -1281,6 +1342,8 @@ void Http2Session::HandleHeadersFrame(const nghttp2_frame* frame) {
     return;
 
   std::vector<nghttp2_header> headers(stream->move_headers());
+  DecrementCurrentSessionMemory(stream->current_headers_length_);
+  stream->current_headers_length_ = 0;
 
   // The headers are passed in above as a queue of nghttp2_header structs.
   // The following converts that into a JS array with the structure:
@@ -1316,6 +1379,7 @@ void Http2Session::HandleHeadersFrame(const nghttp2_frame* frame) {
 // are considered advisory only, so this has no real effect other than to
 // simply let user code know that the priority has changed.
 void Http2Session::HandlePriorityFrame(const nghttp2_frame* frame) {
+  if (js_fields_[kSessionPriorityListenerCount] == 0) return;
   Isolate* isolate = env()->isolate();
   HandleScope scope(isolate);
   Local<Context> context = env()->context();
@@ -1341,13 +1405,18 @@ void Http2Session::HandlePriorityFrame(const nghttp2_frame* frame) {
 // Called by OnFrameReceived when a complete DATA frame has been received.
 // If we know that this was the last DATA frame (because the END_STREAM flag
 // is set), then we'll terminate the readable side of the StreamBase.
-void Http2Session::HandleDataFrame(const nghttp2_frame* frame) {
+int Http2Session::HandleDataFrame(const nghttp2_frame* frame) {
   int32_t id = GetFrameID(frame);
   Debug(this, "handling data frame for stream %d", id);
   Http2Stream* stream = FindStream(id);
 
-  if (!stream->IsDestroyed() && frame->hd.flags & NGHTTP2_FLAG_END_STREAM)
+  if (!stream->IsDestroyed() && frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
     stream->EmitRead(UV_EOF);
+  } else if (frame->hd.length == 0 &&
+           !IsReverted(SECURITY_REVERT_CVE_2019_9518)) {
+    return 1;  // Consider 0-length frame without END_STREAM an error.
+  }
+  return 0;
 }
 
 
@@ -1380,6 +1449,7 @@ void Http2Session::HandleGoawayFrame(const nghttp2_frame* frame) {
 
 // Called by OnFrameReceived when a complete ALTSVC frame has been received.
 void Http2Session::HandleAltSvcFrame(const nghttp2_frame* frame) {
+  if (!(js_fields_[kBitfield] & (1 << kSessionHasAltsvcListeners))) return;
   Isolate* isolate = env()->isolate();
   HandleScope scope(isolate);
   Local<Context> context = env()->context();
@@ -1458,6 +1528,7 @@ void Http2Session::HandlePingFrame(const nghttp2_frame* frame) {
     return;
   }
 
+  if (!(js_fields_[kBitfield] & (1 << kSessionHasPingListeners))) return;
   // Notify the session that a ping occurred
   arg = Buffer::Copy(env(),
                       reinterpret_cast<const char*>(frame->ping.opaque_data),
@@ -1469,6 +1540,9 @@ void Http2Session::HandlePingFrame(const nghttp2_frame* frame) {
 void Http2Session::HandleSettingsFrame(const nghttp2_frame* frame) {
   bool ack = frame->hd.flags & NGHTTP2_FLAG_ACK;
   if (!ack) {
+    js_fields_[kBitfield] &= ~(1 << kSessionRemoteSettingsIsUpToDate);
+    if (!(js_fields_[kBitfield] & (1 << kSessionHasRemoteSettingsListeners)))
+      return;
     // This is not a SETTINGS acknowledgement, notify and return
     MakeCallback(env()->http2session_on_settings_function(), 0, nullptr);
     return;
@@ -1502,9 +1576,23 @@ void Http2Session::HandleSettingsFrame(const nghttp2_frame* frame) {
 void Http2Session::OnStreamAfterWrite(WriteWrap* w, int status) {
   Debug(this, "write finished with status %d", status);
 
+  CHECK_NE(flags_ & SESSION_STATE_WRITE_IN_PROGRESS, 0);
+  flags_ &= ~SESSION_STATE_WRITE_IN_PROGRESS;
+
   // Inform all pending writes about their completion.
   ClearOutgoing(status);
 
+  if ((flags_ & SESSION_STATE_READING_STOPPED) &&
+      nghttp2_session_want_read(session_)) {
+    flags_ &= ~SESSION_STATE_READING_STOPPED;
+    stream_->ReadStart();
+  }
+
+  // If there is more incoming data queued up, consume it.
+  if (stream_buf_offset_ > 0) {
+    ConsumeHTTP2Data();
+  }
+
   if (!(flags_ & SESSION_STATE_WRITE_SCHEDULED)) {
     // Schedule a new write if nghttp2 wants to send data.
     MaybeScheduleWrite();
@@ -1542,10 +1630,13 @@ void Http2Session::MaybeScheduleWrite() {
 }
 
 void Http2Session::MaybeStopReading() {
+  if (flags_ & SESSION_STATE_READING_STOPPED) return;
   int want_read = nghttp2_session_want_read(session_);
   Debug(this, "wants read? %d", want_read);
-  if (want_read == 0)
+  if (want_read == 0 || (flags_ & SESSION_STATE_WRITE_IN_PROGRESS)) {
+    flags_ |= SESSION_STATE_READING_STOPPED;
     stream_->ReadStop();
+  }
 }
 
 // Unset the sending state, finish up all current writes, and reset
@@ -1557,6 +1648,7 @@ void Http2Session::ClearOutgoing(int status) {
 
   if (outgoing_buffers_.size() > 0) {
     outgoing_storage_.clear();
+    outgoing_length_ = 0;
 
     std::vector<nghttp2_stream_write> current_outgoing_buffers_;
     current_outgoing_buffers_.swap(outgoing_buffers_);
@@ -1587,6 +1679,11 @@ void Http2Session::ClearOutgoing(int status) {
   }
 }
 
+void Http2Session::PushOutgoingBuffer(nghttp2_stream_write&& write) {
+  outgoing_length_ += write.buf.len;
+  outgoing_buffers_.emplace_back(std::move(write));
+}
+
 // Queue a given block of data for sending. This always creates a copy,
 // so it is used for the cases in which nghttp2 requests sending of a
 // small chunk of data.
@@ -1599,7 +1696,7 @@ void Http2Session::CopyDataIntoOutgoing(const uint8_t* src, size_t src_length) {
   // of the outgoing_buffers_ vector may invalidate the pointer.
   // The correct base pointers will be set later, before writing to the
   // underlying socket.
-  outgoing_buffers_.emplace_back(nghttp2_stream_write {
+  PushOutgoingBuffer(nghttp2_stream_write {
     uv_buf_init(nullptr, src_length)
   });
 }
@@ -1676,8 +1773,11 @@ uint8_t Http2Session::SendPendingData() {
 
   chunks_sent_since_last_write_++;
 
+  CHECK_EQ(flags_ & SESSION_STATE_WRITE_IN_PROGRESS, 0);
+  flags_ |= SESSION_STATE_WRITE_IN_PROGRESS;
   StreamWriteResult res = underlying_stream()->Write(*bufs, count);
   if (!res.async) {
+    flags_ &= ~SESSION_STATE_WRITE_IN_PROGRESS;
     ClearOutgoing(res.err);
   }
 
@@ -1719,13 +1819,13 @@ int Http2Session::OnSendData(
     if (write.buf.len <= length) {
       // This write does not suffice by itself, so we can consume it completely.
       length -= write.buf.len;
-      session->outgoing_buffers_.emplace_back(std::move(write));
+      session->PushOutgoingBuffer(std::move(write));
       stream->queue_.pop();
       continue;
     }
 
     // Slice off `length` bytes of the first write in the queue.
-    session->outgoing_buffers_.emplace_back(nghttp2_stream_write {
+    session->PushOutgoingBuffer(nghttp2_stream_write {
       uv_buf_init(write.buf.base, length)
     });
     write.buf.base += length;
@@ -1735,7 +1835,7 @@ int Http2Session::OnSendData(
 
   if (frame->data.padlen > 0) {
     // Send padding if that was requested.
-    session->outgoing_buffers_.emplace_back(nghttp2_stream_write {
+    session->PushOutgoingBuffer(nghttp2_stream_write {
       uv_buf_init(const_cast<char*>(zero_bytes_256), frame->data.padlen - 1)
     });
   }
@@ -1772,7 +1872,6 @@ void Http2Session::OnStreamRead(ssize_t nread, const uv_buf_t& buf_) {
   Http2Scope h2scope(this);
   CHECK_NOT_NULL(stream_);
   Debug(this, "receiving %d bytes", nread);
-  CHECK(stream_buf_ab_.IsEmpty());
   AllocatedBuffer buf(env(), buf_);
 
   // Only pass data on if nread > 0
@@ -1783,23 +1882,31 @@ void Http2Session::OnStreamRead(ssize_t nread, const uv_buf_t& buf_) {
     return;
   }
 
+  statistics_.data_received += nread;
+
+  if (UNLIKELY(stream_buf_offset_ > 0)) {
+    // This is a very unlikely case, and should only happen if the ReadStart()
+    // call in OnStreamAfterWrite() immediately provides data. If that does
+    // happen, we concatenate the data we received with the already-stored
+    // pending input data, slicing off the already processed part.
+    AllocatedBuffer new_buf = env()->AllocateManaged(
+        stream_buf_.len - stream_buf_offset_ + nread);
+    memcpy(new_buf.data(),
+           stream_buf_.base + stream_buf_offset_,
+           stream_buf_.len - stream_buf_offset_);
+    memcpy(new_buf.data() + stream_buf_.len - stream_buf_offset_,
+           buf.data(),
+           nread);
+    buf = std::move(new_buf);
+    nread = buf.size();
+    stream_buf_offset_ = 0;
+    stream_buf_ab_.Reset();
+    DecrementCurrentSessionMemory(stream_buf_offset_);
+  }
+
   // Shrink to the actual amount of used data.
   buf.Resize(nread);
-
   IncrementCurrentSessionMemory(nread);
-  OnScopeLeave on_scope_leave([&]() {
-    // Once finished handling this write, reset the stream buffer.
-    // The memory has either been free()d or was handed over to V8.
-    // We use `nread` instead of `buf.size()` here, because the buffer is
-    // cleared as part of the `.ToArrayBuffer()` call below.
-    DecrementCurrentSessionMemory(nread);
-    stream_buf_ab_ = Local<ArrayBuffer>();
-    stream_buf_ = uv_buf_init(nullptr, 0);
-  });
-
-  // Make sure that there was no read previously active.
-  CHECK_NULL(stream_buf_.base);
-  CHECK_EQ(stream_buf_.len, 0);
 
   // Remember the current buffer, so that OnDataChunkReceived knows the
   // offset of a DATA frame's data into the socket read buffer.
@@ -1807,12 +1914,12 @@ void Http2Session::OnStreamRead(ssize_t nread, const uv_buf_t& buf_) {
 
   Isolate* isolate = env()->isolate();
 
-  // Create an array buffer for the read data. DATA frames will be emitted
-  // as slices of this array buffer to avoid having to copy memory.
-  stream_buf_ab_ = buf.ToArrayBuffer();
+  // Store this so we can create an ArrayBuffer for read data from it.
+  // DATA frames will be emitted as slices of that ArrayBuffer to avoid having
+  // to copy memory.
+  stream_buf_allocation_ = std::move(buf);
 
-  statistics_.data_received += nread;
-  ssize_t ret = Write(&stream_buf_, 1);
+  ssize_t ret = ConsumeHTTP2Data();
 
   if (UNLIKELY(ret < 0)) {
     Debug(this, "fatal error receiving data: %d", ret);
@@ -1875,7 +1982,7 @@ Http2Stream::Http2Stream(Http2Session* session,
   if (max_header_pairs_ == 0) {
     max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;
   }
-  current_headers_.reserve(max_header_pairs_);
+  current_headers_.reserve(std::min(max_header_pairs_, 12u));
 
   // Limit the number of header octets
   max_header_length_ =
@@ -1905,6 +2012,7 @@ Http2Stream::~Http2Stream() {
   if (session_ == nullptr)
     return;
   Debug(this, "tearing down stream");
+  session_->DecrementCurrentSessionMemory(current_headers_length_);
   session_->RemoveStream(this);
   session_ = nullptr;
 }
@@ -1919,6 +2027,7 @@ std::string Http2Stream::diagnostic_name() const {
 void Http2Stream::StartHeaders(nghttp2_headers_category category) {
   Debug(this, "starting headers, category: %d", id_, category);
   CHECK(!this->IsDestroyed());
+  session_->DecrementCurrentSessionMemory(current_headers_length_);
   current_headers_length_ = 0;
   current_headers_.clear();
   current_headers_category_ = category;
@@ -2188,8 +2297,12 @@ bool Http2Stream::AddHeader(nghttp2_rcbuf* name,
   CHECK(!this->IsDestroyed());
   if (this->statistics_.first_header == 0)
     this->statistics_.first_header = uv_hrtime();
-  size_t length = nghttp2_rcbuf_get_buf(name).len +
-                  nghttp2_rcbuf_get_buf(value).len + 32;
+  size_t name_len = nghttp2_rcbuf_get_buf(name).len;
+  if (name_len == 0 && !IsReverted(SECURITY_REVERT_CVE_2019_9516)) {
+    return true;  // Ignore headers with empty names.
+  }
+  size_t value_len = nghttp2_rcbuf_get_buf(value).len;
+  size_t length = name_len + value_len + 32;
   // A header can only be added if we have not exceeded the maximum number
   // of headers and the session has memory available for it.
   if (!session_->IsAvailableSessionMemory(length) ||
@@ -2205,6 +2318,7 @@ bool Http2Stream::AddHeader(nghttp2_rcbuf* name,
   nghttp2_rcbuf_incref(name);
   nghttp2_rcbuf_incref(value);
   current_headers_length_ += length;
+  session_->IncrementCurrentSessionMemory(length);
   return true;
 }
 
@@ -2981,6 +3095,16 @@ void Initialize(Local<Object> target,
   NODE_DEFINE_CONSTANT(target, PADDING_BUF_MAX_PAYLOAD_LENGTH);
   NODE_DEFINE_CONSTANT(target, PADDING_BUF_RETURN_VALUE);
 
+  NODE_DEFINE_CONSTANT(target, kBitfield);
+  NODE_DEFINE_CONSTANT(target, kSessionPriorityListenerCount);
+  NODE_DEFINE_CONSTANT(target, kSessionFrameErrorListenerCount);
+  NODE_DEFINE_CONSTANT(target, kSessionUint8FieldCount);
+
+  NODE_DEFINE_CONSTANT(target, kSessionHasRemoteSettingsListeners);
+  NODE_DEFINE_CONSTANT(target, kSessionRemoteSettingsIsUpToDate);
+  NODE_DEFINE_CONSTANT(target, kSessionHasPingListeners);
+  NODE_DEFINE_CONSTANT(target, kSessionHasAltsvcListeners);
+
   // Method to fetch the nghttp2 string description of an nghttp2 error code
   env->SetMethod(target, "nghttp2ErrorString", HttpErrorString);
 
diff --git a/src/node_http2.h b/src/node_http2.h
index d9636628c25939..9c032f02d17ac7 100644
--- a/src/node_http2.h
+++ b/src/node_http2.h
@@ -335,6 +335,9 @@ enum session_state_flags {
   SESSION_STATE_CLOSED = 0x4,
   SESSION_STATE_CLOSING = 0x8,
   SESSION_STATE_SENDING = 0x10,
+  SESSION_STATE_WRITE_IN_PROGRESS = 0x20,
+  SESSION_STATE_READING_STOPPED = 0x40,
+  SESSION_STATE_NGHTTP2_RECV_PAUSED = 0x80
 };
 
 typedef uint32_t(*get_setting)(nghttp2_session* session,
@@ -672,6 +675,23 @@ class Http2Stream::Provider::Stream : public Http2Stream::Provider {
                         void* user_data);
 };
 
+// Indices for js_fields_, which serves as a way to communicate data with JS
+// land fast. In particular, we store information about the number/presence
+// of certain event listeners in JS, and skip calls from C++ into JS if they
+// are missing.
+enum SessionUint8Fields {
+  kBitfield,  // See below
+  kSessionPriorityListenerCount,
+  kSessionFrameErrorListenerCount,
+  kSessionUint8FieldCount
+};
+
+enum SessionBitfieldFlags {
+  kSessionHasRemoteSettingsListeners,
+  kSessionRemoteSettingsIsUpToDate,
+  kSessionHasPingListeners,
+  kSessionHasAltsvcListeners
+};
 
 class Http2Session : public AsyncWrap, public StreamListener {
  public:
@@ -748,14 +768,15 @@ class Http2Session : public AsyncWrap, public StreamListener {
   // Indicates whether there currently exist outgoing buffers for this stream.
   bool HasWritesOnSocketForStream(Http2Stream* stream);
 
-  // Write data to the session
-  ssize_t Write(const uv_buf_t* bufs, size_t nbufs);
+  // Write data from stream_buf_ to the session
+  ssize_t ConsumeHTTP2Data();
 
   void MemoryInfo(MemoryTracker* tracker) const override {
     tracker->TrackField("streams", streams_);
     tracker->TrackField("outstanding_pings", outstanding_pings_);
     tracker->TrackField("outstanding_settings", outstanding_settings_);
     tracker->TrackField("outgoing_buffers", outgoing_buffers_);
+    tracker->TrackFieldWithSize("stream_buf", stream_buf_.len);
     tracker->TrackFieldWithSize("outgoing_storage", outgoing_storage_.size());
     tracker->TrackFieldWithSize("pending_rst_streams",
                                 pending_rst_streams_.size() * sizeof(int32_t));
@@ -814,6 +835,7 @@ class Http2Session : public AsyncWrap, public StreamListener {
   }
 
   void DecrementCurrentSessionMemory(uint64_t amount) {
+    DCHECK_LE(amount, current_session_memory_);
     current_session_memory_ -= amount;
   }
 
@@ -860,7 +882,7 @@ class Http2Session : public AsyncWrap, public StreamListener {
                             size_t maxPayloadLen);
 
   // Frame Handler
-  void HandleDataFrame(const nghttp2_frame* frame);
+  int HandleDataFrame(const nghttp2_frame* frame);
   void HandleGoawayFrame(const nghttp2_frame* frame);
   void HandleHeadersFrame(const nghttp2_frame* frame);
   void HandlePriorityFrame(const nghttp2_frame* frame);
@@ -949,6 +971,9 @@ class Http2Session : public AsyncWrap, public StreamListener {
   // The underlying nghttp2_session handle
   nghttp2_session* session_;
 
+  // JS-accessible numeric fields, as indexed by SessionUint8Fields.
+  uint8_t js_fields_[kSessionUint8FieldCount] = {};
+
   // The session type: client or server
   nghttp2_session_type session_type_;
 
@@ -973,7 +998,11 @@ class Http2Session : public AsyncWrap, public StreamListener {
   uint32_t chunks_sent_since_last_write_ = 0;
 
   uv_buf_t stream_buf_ = uv_buf_init(nullptr, 0);
-  v8::Local<v8::ArrayBuffer> stream_buf_ab_;
+  // When processing input data, either stream_buf_ab_ or stream_buf_allocation_
+  // will be set. stream_buf_ab_ is lazily created from stream_buf_allocation_.
+  v8::Global<v8::ArrayBuffer> stream_buf_ab_;
+  AllocatedBuffer stream_buf_allocation_;
+  size_t stream_buf_offset_ = 0;
 
   size_t max_outstanding_pings_ = DEFAULT_MAX_PINGS;
   std::queue<std::unique_ptr<Http2Ping>> outstanding_pings_;
@@ -983,8 +1012,17 @@ class Http2Session : public AsyncWrap, public StreamListener {
 
   std::vector<nghttp2_stream_write> outgoing_buffers_;
   std::vector<uint8_t> outgoing_storage_;
+  size_t outgoing_length_ = 0;
   std::vector<int32_t> pending_rst_streams_;
-
+  // Count streams that have been rejected while being opened. Exceeding a fixed
+  // limit will result in the session being destroyed, as an indication of a
+  // misbehaving peer. This counter is reset once new streams are being
+  // accepted again.
+  int32_t rejected_stream_count_ = 0;
+  // Also use the invalid frame count as a measure for rejecting input frames.
+  int32_t invalid_frame_count_ = 0;
+
+  void PushOutgoingBuffer(nghttp2_stream_write&& write);
   void CopyDataIntoOutgoing(const uint8_t* src, size_t src_length);
   void ClearOutgoing(int status);
 
diff --git a/src/node_revert.h b/src/node_revert.h
index 38e2ba71053691..66161c9c9b2048 100644
--- a/src/node_revert.h
+++ b/src/node_revert.h
@@ -15,8 +15,14 @@
  **/
 namespace node {
 
-#define SECURITY_REVERSIONS(XX)
+#define SECURITY_REVERSIONS(XX)                                            \
+  XX(CVE_2019_9512, "CVE-2019-9512", "HTTP/2 Ping/Settings Flood")         \
+  XX(CVE_2019_9514, "CVE-2019-9514", "HTTP/2 Reset Flood")                 \
+  XX(CVE_2019_9516, "CVE-2019-9516", "HTTP/2 0-Length Headers Leak")       \
+  XX(CVE_2019_9518, "CVE-2019-9518", "HTTP/2 Empty DATA Frame Flooding")   \
 //  XX(CVE_2016_PEND, "CVE-2016-PEND", "Vulnerability Title")
+  // TODO(addaleax): Remove all of the above before Node.js 13 as the comment
+  // at the start of the file indicates.
 
 enum reversion {
 #define V(code, ...) SECURITY_REVERT_##code,
diff --git a/test/parallel/test-http2-large-write-multiple-requests.js b/test/parallel/test-http2-large-write-multiple-requests.js
new file mode 100644
index 00000000000000..0d65c3479b409d
--- /dev/null
+++ b/test/parallel/test-http2-large-write-multiple-requests.js
@@ -0,0 +1,39 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const fixtures = require('../common/fixtures');
+const assert = require('assert');
+const http2 = require('http2');
+
+const content = fixtures.readSync('person-large.jpg');
+
+const server = http2.createServer({
+  maxSessionMemory: 1000
+});
+server.on('stream', (stream, headers) => {
+  stream.respond({
+    'content-type': 'image/jpeg',
+    ':status': 200
+  });
+  stream.end(content);
+});
+server.unref();
+
+server.listen(0, common.mustCall(() => {
+  const client = http2.connect(`http://localhost:${server.address().port}/`);
+
+  let finished = 0;
+  for (let i = 0; i < 100; i++) {
+    const req = client.request({ ':path': '/' }).end();
+    const chunks = [];
+    req.on('data', (chunk) => {
+      chunks.push(chunk);
+    });
+    req.on('end', common.mustCall(() => {
+      assert.deepStrictEqual(Buffer.concat(chunks), content);
+      if (++finished === 100) client.close();
+    }));
+  }
+}));
diff --git a/test/parallel/test-http2-reset-flood.js b/test/parallel/test-http2-reset-flood.js
new file mode 100644
index 00000000000000..a6553401fbb6e7
--- /dev/null
+++ b/test/parallel/test-http2-reset-flood.js
@@ -0,0 +1,79 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const http2 = require('http2');
+const net = require('net');
+const { Worker, parentPort } = require('worker_threads');
+
+// Verify that creating a number of invalid HTTP/2 streams will eventually
+// result in the peer closing the session.
+// This test uses separate threads for client and server to avoid
+// the two event loops intermixing, as we are writing in a busy loop here.
+
+if (process.env.HAS_STARTED_WORKER) {
+  const server = http2.createServer();
+  server.on('stream', (stream) => {
+    stream.respond({
+      'content-type': 'text/plain',
+      ':status': 200
+    });
+    stream.end('Hello, world!\n');
+  });
+  server.listen(0, () => parentPort.postMessage(server.address().port));
+  return;
+}
+
+process.env.HAS_STARTED_WORKER = 1;
+const worker = new Worker(__filename).on('message', common.mustCall((port) => {
+  const h2header = Buffer.alloc(9);
+  const conn = net.connect(port);
+
+  conn.write('PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n');
+
+  h2header[3] = 4;  // Send a settings frame.
+  conn.write(Buffer.from(h2header));
+
+  let inbuf = Buffer.alloc(0);
+  let state = 'settingsHeader';
+  let settingsFrameLength;
+  conn.on('data', (chunk) => {
+    inbuf = Buffer.concat([inbuf, chunk]);
+    switch (state) {
+      case 'settingsHeader':
+        if (inbuf.length < 9) return;
+        settingsFrameLength = inbuf.readIntBE(0, 3);
+        inbuf = inbuf.slice(9);
+        state = 'readingSettings';
+        // Fallthrough
+      case 'readingSettings':
+        if (inbuf.length < settingsFrameLength) return;
+        inbuf = inbuf.slice(settingsFrameLength);
+        h2header[3] = 4;  // Send a settings ACK.
+        h2header[4] = 1;
+        conn.write(Buffer.from(h2header));
+        state = 'ignoreInput';
+        writeRequests();
+    }
+  });
+
+  let gotError = false;
+
+  function writeRequests() {
+    for (let i = 1; !gotError; i += 2) {
+      h2header[3] = 1;  // HEADERS
+      h2header[4] = 0x5;  // END_HEADERS|END_STREAM
+      h2header.writeIntBE(1, 0, 3);  // Length: 1
+      h2header.writeIntBE(i, 5, 4);  // Stream ID
+      // 0x88 = :status: 200
+      conn.write(Buffer.concat([h2header, Buffer.from([0x88])]));
+    }
+  }
+
+  conn.once('error', common.mustCall(() => {
+    gotError = true;
+    worker.terminate();
+    conn.destroy();
+  }));
+}));
diff --git a/test/parallel/test-http2-zero-length-header.js b/test/parallel/test-http2-zero-length-header.js
new file mode 100644
index 00000000000000..7b142d75f003b6
--- /dev/null
+++ b/test/parallel/test-http2-zero-length-header.js
@@ -0,0 +1,25 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const assert = require('assert');
+const http2 = require('http2');
+
+const server = http2.createServer();
+server.on('stream', (stream, headers) => {
+  assert.deepStrictEqual(headers, {
+    ':scheme': 'http',
+    ':authority': `localhost:${server.address().port}`,
+    ':method': 'GET',
+    ':path': '/',
+    'bar': '',
+    '__proto__': null
+  });
+  stream.session.destroy();
+  server.close();
+});
+server.listen(0, common.mustCall(() => {
+  const client = http2.connect(`http://localhost:${server.address().port}/`);
+  client.request({ ':path': '/', '': 'foo', 'bar': '' }).end();
+}));