diff --git a/deps/undici/src/docs/api/MockPool.md b/deps/undici/src/docs/api/MockPool.md
index c86f9a30adb8e0..923c157aa64657 100644
--- a/deps/undici/src/docs/api/MockPool.md
+++ b/deps/undici/src/docs/api/MockPool.md
@@ -63,7 +63,8 @@ Returns: `MockInterceptor` corresponding to the input options.
 
 We can define the behaviour of an intercepted request with the following options.
 
-* **reply** `(statusCode: number, replyData: string | Buffer | object | MockInterceptor.MockResponseDataHandler, responseOptions?: MockResponseOptions) => MockScope` - define a reply for a matching request. You can define this as a callback to read incoming request data. Default for `responseOptions` is `{}`.
+* **reply** `(statusCode: number, replyData: string | Buffer | object | MockInterceptor.MockResponseDataHandler, responseOptions?: MockResponseOptions) => MockScope` - define a reply for a matching request. You can define the replyData as a callback to read incoming request data. Default for `responseOptions` is `{}`.
+* **reply** `(callback: MockInterceptor.MockReplyOptionsCallback) => MockScope` - define a reply for a matching request, allowing dynamic mocking of all reply options rather than just the data.
 * **replyWithError** `(error: Error) => MockScope` - define an error for a matching request to throw.
 * **defaultReplyHeaders** `(headers: Record<string, string>) => MockInterceptor` - define default headers to be included in subsequent replies. These are in addition to headers on a specific reply.
 * **defaultReplyTrailers** `(trailers: Record<string, string>) => MockInterceptor` - define default trailers to be included in subsequent replies. These are in addition to trailers on a specific reply.
diff --git a/deps/undici/src/lib/cookies/index.js b/deps/undici/src/lib/cookies/index.js
index def04f5bc4ac72..c9c1f28ee1ff51 100644
--- a/deps/undici/src/lib/cookies/index.js
+++ b/deps/undici/src/lib/cookies/index.js
@@ -83,7 +83,8 @@ function getSetCookies (headers) {
     return []
   }
 
-  return cookies.map((pair) => parseSetCookie(pair[1]))
+  // In older versions of undici, cookies is a list of name:value.
+  return cookies.map((pair) => parseSetCookie(Array.isArray(pair) ? pair[1] : pair))
 }
 
 /**
diff --git a/deps/undici/src/lib/core/request.js b/deps/undici/src/lib/core/request.js
index 7271bc64f24901..adb5bfcb3a86d4 100644
--- a/deps/undici/src/lib/core/request.js
+++ b/deps/undici/src/lib/core/request.js
@@ -304,6 +304,9 @@ function processHeader (request, key, val) {
     key.length === 4 &&
     key.toLowerCase() === 'host'
   ) {
+    if (headerCharRegex.exec(val) !== null) {
+      throw new InvalidArgumentError(`invalid ${key} header`)
+    }
     // Consumed by Client
     request.host = val
   } else if (
diff --git a/deps/undici/src/lib/core/util.js b/deps/undici/src/lib/core/util.js
index 6f38ffc8a4de0b..3b9b56cb64d1ea 100644
--- a/deps/undici/src/lib/core/util.js
+++ b/deps/undici/src/lib/core/util.js
@@ -213,25 +213,42 @@ function parseHeaders (headers, obj = {}) {
   for (let i = 0; i < headers.length; i += 2) {
     const key = headers[i].toString().toLowerCase()
     let val = obj[key]
+
+    const encoding = key.length === 19 && key === 'content-disposition'
+      ? 'latin1'
+      : 'utf8'
+
     if (!val) {
       if (Array.isArray(headers[i + 1])) {
         obj[key] = headers[i + 1]
       } else {
-        obj[key] = headers[i + 1].toString()
+        obj[key] = headers[i + 1].toString(encoding)
       }
     } else {
       if (!Array.isArray(val)) {
         val = [val]
         obj[key] = val
       }
-      val.push(headers[i + 1].toString())
+      val.push(headers[i + 1].toString(encoding))
     }
   }
   return obj
 }
 
 function parseRawHeaders (headers) {
-  return headers.map(header => header.toString())
+  const ret = []
+  for (let n = 0; n < headers.length; n += 2) {
+    const key = headers[n + 0].toString()
+
+    const encoding = key.length === 19 && key.toLowerCase() === 'content-disposition'
+      ? 'latin1'
+      : 'utf8'
+
+    const val = headers[n + 1].toString(encoding)
+
+    ret.push(key, val)
+  }
+  return ret
 }
 
 function isBuffer (buffer) {
diff --git a/deps/undici/src/lib/fetch/headers.js b/deps/undici/src/lib/fetch/headers.js
index 0febd114db5fa0..ea3b9a14a43c74 100644
--- a/deps/undici/src/lib/fetch/headers.js
+++ b/deps/undici/src/lib/fetch/headers.js
@@ -11,6 +11,7 @@ const {
   isValidHeaderValue
 } = require('./util')
 const { webidl } = require('./webidl')
+const assert = require('assert')
 
 const kHeadersMap = Symbol('headers map')
 const kHeadersSortedMap = Symbol('headers map sorted')
@@ -23,10 +24,12 @@ function headerValueNormalize (potentialValue) {
   //  To normalize a byte sequence potentialValue, remove
   //  any leading and trailing HTTP whitespace bytes from
   //  potentialValue.
-  return potentialValue.replace(
-    /^[\r\n\t ]+|[\r\n\t ]+$/g,
-    ''
-  )
+
+  // Trimming the end with `.replace()` and a RegExp is typically subject to
+  // ReDoS. This is safer and faster.
+  let i = potentialValue.length
+  while (/[\r\n\t ]/.test(potentialValue.charAt(--i)));
+  return potentialValue.slice(0, i + 1).replace(/^[\r\n\t ]+/, '')
 }
 
 function fill (headers, object) {
@@ -115,7 +118,7 @@ class HeadersList {
 
     if (lowercaseName === 'set-cookie') {
       this.cookies ??= []
-      this.cookies.push([name, value])
+      this.cookies.push(value)
     }
   }
 
@@ -125,7 +128,7 @@ class HeadersList {
     const lowercaseName = name.toLowerCase()
 
     if (lowercaseName === 'set-cookie') {
-      this.cookies = [[name, value]]
+      this.cookies = [value]
     }
 
     // 1. If list contains name, then set the value of
@@ -383,18 +386,74 @@ class Headers {
     return this[kHeadersList].set(name, value)
   }
 
+  // https://fetch.spec.whatwg.org/#dom-headers-getsetcookie
+  getSetCookie () {
+    webidl.brandCheck(this, Headers)
+
+    // 1. If this’s header list does not contain `Set-Cookie`, then return « ».
+    // 2. Return the values of all headers in this’s header list whose name is
+    //    a byte-case-insensitive match for `Set-Cookie`, in order.
+
+    const list = this[kHeadersList].cookies
+
+    if (list) {
+      return [...list]
+    }
+
+    return []
+  }
+
+  // https://fetch.spec.whatwg.org/#concept-header-list-sort-and-combine
   get [kHeadersSortedMap] () {
-    if (!this[kHeadersList][kHeadersSortedMap]) {
-      this[kHeadersList][kHeadersSortedMap] = new Map([...this[kHeadersList]].sort((a, b) => a[0] < b[0] ? -1 : 1))
+    if (this[kHeadersList][kHeadersSortedMap]) {
+      return this[kHeadersList][kHeadersSortedMap]
     }
-    return this[kHeadersList][kHeadersSortedMap]
+
+    // 1. Let headers be an empty list of headers with the key being the name
+    //    and value the value.
+    const headers = []
+
+    // 2. Let names be the result of convert header names to a sorted-lowercase
+    //    set with all the names of the headers in list.
+    const names = [...this[kHeadersList]].sort((a, b) => a[0] < b[0] ? -1 : 1)
+    const cookies = this[kHeadersList].cookies
+
+    // 3. For each name of names:
+    for (const [name, value] of names) {
+      // 1. If name is `set-cookie`, then:
+      if (name === 'set-cookie') {
+        // 1. Let values be a list of all values of headers in list whose name
+        //    is a byte-case-insensitive match for name, in order.
+
+        // 2. For each value of values:
+        // 1. Append (name, value) to headers.
+        for (const value of cookies) {
+          headers.push([name, value])
+        }
+      } else {
+        // 2. Otherwise:
+
+        // 1. Let value be the result of getting name from list.
+
+        // 2. Assert: value is non-null.
+        assert(value !== null)
+
+        // 3. Append (name, value) to headers.
+        headers.push([name, value])
+      }
+    }
+
+    this[kHeadersList][kHeadersSortedMap] = headers
+
+    // 4. Return headers.
+    return headers
   }
 
   keys () {
     webidl.brandCheck(this, Headers)
 
     return makeIterator(
-      () => [...this[kHeadersSortedMap].entries()],
+      () => [...this[kHeadersSortedMap].values()],
       'Headers',
       'key'
     )
@@ -404,7 +463,7 @@ class Headers {
     webidl.brandCheck(this, Headers)
 
     return makeIterator(
-      () => [...this[kHeadersSortedMap].entries()],
+      () => [...this[kHeadersSortedMap].values()],
       'Headers',
       'value'
     )
@@ -414,7 +473,7 @@ class Headers {
     webidl.brandCheck(this, Headers)
 
     return makeIterator(
-      () => [...this[kHeadersSortedMap].entries()],
+      () => [...this[kHeadersSortedMap].values()],
       'Headers',
       'key+value'
     )
diff --git a/deps/undici/src/lib/fetch/request.js b/deps/undici/src/lib/fetch/request.js
index 7264d152f87631..eca7b060e0ea1f 100644
--- a/deps/undici/src/lib/fetch/request.js
+++ b/deps/undici/src/lib/fetch/request.js
@@ -28,6 +28,7 @@ const { getGlobalOrigin } = require('./global')
 const { URLSerializer } = require('./dataURL')
 const { kHeadersList } = require('../core/symbols')
 const assert = require('assert')
+const { setMaxListeners, getEventListeners, defaultMaxListeners } = require('events')
 
 let TransformStream = globalThis.TransformStream
 
@@ -352,6 +353,11 @@ class Request {
         const abort = function () {
           acRef.deref()?.abort(this.reason)
         }
+
+        if (getEventListeners(signal, 'abort').length >= defaultMaxListeners) {
+          setMaxListeners(100, signal)
+        }
+
         signal.addEventListener('abort', abort, { once: true })
         requestFinalizer.register(this, { signal, abort })
       }
diff --git a/deps/undici/src/lib/mock/mock-utils.js b/deps/undici/src/lib/mock/mock-utils.js
index 9dc414d0a3578f..42ea185cc0ebd0 100644
--- a/deps/undici/src/lib/mock/mock-utils.js
+++ b/deps/undici/src/lib/mock/mock-utils.js
@@ -188,7 +188,11 @@ function buildKey (opts) {
 }
 
 function generateKeyValues (data) {
-  return Object.entries(data).reduce((keyValuePairs, [key, value]) => [...keyValuePairs, key, value], [])
+  return Object.entries(data).reduce((keyValuePairs, [key, value]) => [
+    ...keyValuePairs,
+    Buffer.from(`${key}`),
+    Array.isArray(value) ? value.map(x => Buffer.from(`${x}`)) : Buffer.from(`${value}`)
+  ], [])
 }
 
 /**
diff --git a/deps/undici/src/package.json b/deps/undici/src/package.json
index af56b2ab98fc5e..c664a9af9b3d32 100644
--- a/deps/undici/src/package.json
+++ b/deps/undici/src/package.json
@@ -1,6 +1,6 @@
 {
   "name": "undici",
-  "version": "5.18.0",
+  "version": "5.19.1",
   "description": "An HTTP/1.1 client, written from scratch for Node.js",
   "homepage": "https://undici.nodejs.org",
   "bugs": {
diff --git a/deps/undici/src/types/connector.d.ts b/deps/undici/src/types/connector.d.ts
index 2b28771af2a6cc..d53d7952b5c9e0 100644
--- a/deps/undici/src/types/connector.d.ts
+++ b/deps/undici/src/types/connector.d.ts
@@ -10,6 +10,8 @@ declare namespace buildConnector {
     socketPath?: string | null;
     timeout?: number | null;
     port?: number;
+    keepAlive?: boolean | null;
+    keepAliveInitialDelay?: number | null;
   }
 
   export interface Options {
diff --git a/deps/undici/src/types/fetch.d.ts b/deps/undici/src/types/fetch.d.ts
index 58bd4d2a76919a..fa4619c9182739 100644
--- a/deps/undici/src/types/fetch.d.ts
+++ b/deps/undici/src/types/fetch.d.ts
@@ -59,6 +59,7 @@ export declare class Headers implements SpecIterable<[string, string]> {
   readonly get: (name: string) => string | null
   readonly has: (name: string) => boolean
   readonly set: (name: string, value: string) => void
+  readonly getSetCookie: () => string[]
   readonly forEach: (
     callbackfn: (value: string, key: string, iterable: Headers) => void,
     thisArg?: unknown
diff --git a/deps/undici/undici.js b/deps/undici/undici.js
index 9fd6547bd9529d..85070025e90576 100644
--- a/deps/undici/undici.js
+++ b/deps/undici/undici.js
@@ -438,24 +438,32 @@ var require_util = __commonJS({
       for (let i = 0; i < headers.length; i += 2) {
         const key = headers[i].toString().toLowerCase();
         let val = obj[key];
+        const encoding = key.length === 19 && key === "content-disposition" ? "latin1" : "utf8";
         if (!val) {
           if (Array.isArray(headers[i + 1])) {
             obj[key] = headers[i + 1];
           } else {
-            obj[key] = headers[i + 1].toString();
+            obj[key] = headers[i + 1].toString(encoding);
           }
         } else {
           if (!Array.isArray(val)) {
             val = [val];
             obj[key] = val;
           }
-          val.push(headers[i + 1].toString());
+          val.push(headers[i + 1].toString(encoding));
         }
       }
       return obj;
     }
     function parseRawHeaders(headers) {
-      return headers.map((header) => header.toString());
+      const ret = [];
+      for (let n = 0; n < headers.length; n += 2) {
+        const key = headers[n + 0].toString();
+        const encoding = key.length === 19 && key.toLowerCase() === "content-disposition" ? "latin1" : "utf8";
+        const val = headers[n + 1].toString(encoding);
+        ret.push(key, val);
+      }
+      return ret;
     }
     function isBuffer(buffer) {
       return buffer instanceof Uint8Array || Buffer.isBuffer(buffer);
@@ -1607,10 +1615,14 @@ var require_headers = __commonJS({
       isValidHeaderValue
     } = require_util2();
     var { webidl } = require_webidl();
+    var assert = require("assert");
     var kHeadersMap = Symbol("headers map");
     var kHeadersSortedMap = Symbol("headers map sorted");
     function headerValueNormalize(potentialValue) {
-      return potentialValue.replace(/^[\r\n\t ]+|[\r\n\t ]+$/g, "");
+      let i = potentialValue.length;
+      while (/[\r\n\t ]/.test(potentialValue.charAt(--i)))
+        ;
+      return potentialValue.slice(0, i + 1).replace(/^[\r\n\t ]+/, "");
     }
     function fill(headers, object) {
       if (Array.isArray(object)) {
@@ -1669,14 +1681,14 @@ var require_headers = __commonJS({
         }
         if (lowercaseName === "set-cookie") {
           this.cookies ??= [];
-          this.cookies.push([name, value]);
+          this.cookies.push(value);
         }
       }
       set(name, value) {
         this[kHeadersSortedMap] = null;
         const lowercaseName = name.toLowerCase();
         if (lowercaseName === "set-cookie") {
-          this.cookies = [[name, value]];
+          this.cookies = [value];
         }
         return this[kHeadersMap].set(lowercaseName, { name, value });
       }
@@ -1812,23 +1824,45 @@ var require_headers = __commonJS({
         }
         return this[kHeadersList].set(name, value);
       }
+      getSetCookie() {
+        webidl.brandCheck(this, Headers);
+        const list = this[kHeadersList].cookies;
+        if (list) {
+          return [...list];
+        }
+        return [];
+      }
       get [kHeadersSortedMap]() {
-        if (!this[kHeadersList][kHeadersSortedMap]) {
-          this[kHeadersList][kHeadersSortedMap] = new Map([...this[kHeadersList]].sort((a, b) => a[0] < b[0] ? -1 : 1));
+        if (this[kHeadersList][kHeadersSortedMap]) {
+          return this[kHeadersList][kHeadersSortedMap];
+        }
+        const headers = [];
+        const names = [...this[kHeadersList]].sort((a, b) => a[0] < b[0] ? -1 : 1);
+        const cookies = this[kHeadersList].cookies;
+        for (const [name, value] of names) {
+          if (name === "set-cookie") {
+            for (const value2 of cookies) {
+              headers.push([name, value2]);
+            }
+          } else {
+            assert(value !== null);
+            headers.push([name, value]);
+          }
         }
-        return this[kHeadersList][kHeadersSortedMap];
+        this[kHeadersList][kHeadersSortedMap] = headers;
+        return headers;
       }
       keys() {
         webidl.brandCheck(this, Headers);
-        return makeIterator(() => [...this[kHeadersSortedMap].entries()], "Headers", "key");
+        return makeIterator(() => [...this[kHeadersSortedMap].values()], "Headers", "key");
       }
       values() {
         webidl.brandCheck(this, Headers);
-        return makeIterator(() => [...this[kHeadersSortedMap].entries()], "Headers", "value");
+        return makeIterator(() => [...this[kHeadersSortedMap].values()], "Headers", "value");
       }
       entries() {
         webidl.brandCheck(this, Headers);
-        return makeIterator(() => [...this[kHeadersSortedMap].entries()], "Headers", "key+value");
+        return makeIterator(() => [...this[kHeadersSortedMap].values()], "Headers", "key+value");
       }
       forEach(callbackFn, thisArg = globalThis) {
         webidl.brandCheck(this, Headers);
@@ -6933,6 +6967,7 @@ var require_request = __commonJS({
     var { URLSerializer } = require_dataURL();
     var { kHeadersList } = require_symbols();
     var assert = require("assert");
+    var { setMaxListeners, getEventListeners, defaultMaxListeners } = require("events");
     var TransformStream = globalThis.TransformStream;
     var kInit = Symbol("init");
     var requestFinalizer = new FinalizationRegistry(({ signal, abort }) => {
@@ -7094,6 +7129,9 @@ var require_request = __commonJS({
             const abort = function() {
               acRef.deref()?.abort(this.reason);
             };
+            if (getEventListeners(signal, "abort").length >= defaultMaxListeners) {
+              setMaxListeners(100, signal);
+            }
             signal.addEventListener("abort", abort, { once: true });
             requestFinalizer.register(this, { signal, abort });
           }
@@ -8149,6 +8187,9 @@ var require_request2 = __commonJS({
         return;
       }
       if (request.host === null && key.length === 4 && key.toLowerCase() === "host") {
+        if (headerCharRegex.exec(val) !== null) {
+          throw new InvalidArgumentError(`invalid ${key} header`);
+        }
         request.host = val;
       } else if (request.contentLength === null && key.length === 14 && key.toLowerCase() === "content-length") {
         request.contentLength = parseInt(val, 10);
diff --git a/src/undici_version.h b/src/undici_version.h
index 89b01122b24b5f..620cd358695e17 100644
--- a/src/undici_version.h
+++ b/src/undici_version.h
@@ -2,5 +2,5 @@
 // Refer to tools/update-undici.sh
 #ifndef SRC_UNDICI_VERSION_H_
 #define SRC_UNDICI_VERSION_H_
-#define UNDICI_VERSION "5.18.0"
+#define UNDICI_VERSION "5.19.1"
 #endif  // SRC_UNDICI_VERSION_H_