Ignore certain data-* attributes in rails-ujs when element is contenteditable

There is a potential DOM based cross-site scripting issue in rails-ujs
which leverages the Clipboard API to target HTML elements that are
assigned the contenteditable attribute. This has the potential to occur
when pasting malicious HTML content from the clipboard that includes
a data-method, data-disable-with or data-remote attribute.

[CVE-2023-23913]

Author: fresh-eggs

actionview/app/assets/javascripts/rails-ujs/features/disable.coffee

@@ -1,6 +1,6 @@
 #= require_tree ../utils
 
-{ matches, getData, setData, stopEverything, formElements } = Rails
+{ matches, getData, setData, stopEverything, formElements, isContentEditable } = Rails
 
 Rails.handleDisabledElement = (e) ->
   element = this
@@ -14,6 +14,9 @@ Rails.enableElement = (e) ->
   else
     element = e
 
+  if isContentEditable(element)
+    return
+
   if matches(element, Rails.linkDisableSelector)
     enableLinkElement(element)
   else if matches(element, Rails.buttonDisableSelector) or matches(element, Rails.formEnableSelector)
@@ -24,6 +27,10 @@ Rails.enableElement = (e) ->
 # Unified function to disable an element (link, button and form)
 Rails.disableElement = (e) ->
   element = if e instanceof Event then e.target else e
+
+  if isContentEditable(element)
+    return
+
   if matches(element, Rails.linkDisableSelector)
     disableLinkElement(element)
   else if matches(element, Rails.buttonDisableSelector) or matches(element, Rails.formDisableSelector)

actionview/app/assets/javascripts/rails-ujs/features/method.coffee

@@ -1,6 +1,7 @@
 #= require_tree ../utils
 
 { stopEverything } = Rails
+{ isContentEditable } = Rails
 
 # Handles "data-method" on links such as:
 # <a href="/users/5" data-method="delete" rel="nofollow" data-confirm="Are you sure?">Delete</a>
@@ -9,6 +10,9 @@ Rails.handleMethod = (e) ->
   method = link.getAttribute('data-method')
   return unless method
 
+  if isContentEditable(this)
+    return
+
   href = Rails.href(link)
   csrfToken = Rails.csrfToken()
   csrfParam = Rails.csrfParam()

actionview/app/assets/javascripts/rails-ujs/features/remote.coffee

@@ -4,7 +4,8 @@
   matches, getData, setData
   fire, stopEverything
   ajax, isCrossDomain
-  serializeElement
+  serializeElement,
+  isContentEditable
 } = Rails
 
 # Checks "data-remote" if true to handle the request through a XHR request.
@@ -21,6 +22,10 @@ Rails.handleRemote = (e) ->
     fire(element, 'ajax:stopped')
     return false
 
+  if isContentEditable(element)
+    fire(element, 'ajax:stopped')
+    return false
+
   withCredentials = element.getAttribute('data-with-credentials')
   dataType = element.getAttribute('data-type') or 'script'
 

actionview/app/assets/javascripts/rails-ujs/utils/dom.coffee

@@ -29,6 +29,18 @@ Rails.setData = (element, key, value) ->
   element[expando] ?= {}
   element[expando][key] = value
 
+Rails.isContentEditable = (element) ->
+  isEditable = false
+  loop
+    if(element.isContentEditable)
+      isEditable = true
+      break
+
+    element = element.parentElement
+    break unless(element)
+
+  return isEditable
+
 # a wrapper for document.querySelectorAll
 # returns an Array
 Rails.$ = (selector) ->

actionview/test/ujs/public/test/data-disable-with.js

@@ -37,6 +37,10 @@ module('data-disable-with', {
       'data-url': '/echo',
       'data-disable-with': 'clicking...'
     }))
+
+    $('#qunit-fixture').append($('<div />', {
+      id: 'edit-div', 'contenteditable': 'true'
+    }))
   },
   teardown: function() {
     $(document).unbind('iframe:loaded')
@@ -432,3 +436,21 @@ asyncTest('button[data-remote][data-disable-with] re-enables when `ajax:error` e
     start()
   }, 30)
 })
+
+asyncTest('form button with "data-disable-with" attribute and contenteditable is not modified', 6, function() {
+  var form = $('form[data-remote]'), button = $('<button data-disable-with="submitting ..." name="submit2">Submit</button>')
+
+  var contenteditable_div = $('#qunit-fixture').find('div')
+  form.append(button)
+  contenteditable_div.append(form)
+
+  App.checkEnabledState(button, 'Submit')
+
+  setTimeout(function() {
+    App.checkEnabledState(button, 'Submit')
+    start()
+  }, 13)
+  form.triggerNative('submit')
+
+  App.checkEnabledState(button, 'Submit')
+})

actionview/test/ujs/public/test/data-method.js

@@ -5,6 +5,10 @@ module('data-method', {
     $('#qunit-fixture').append($('<a />', {
       href: '/echo', 'data-method': 'delete', text: 'destroy!'
     }))
+
+    $('#qunit-fixture').append($('<div />', {
+      id: 'edit-div', 'contenteditable': 'true'
+    }))
   },
   teardown: function() {
     $(document).unbind('iframe:loaded')
@@ -82,4 +86,19 @@ asyncTest('link with "data-method" and cross origin', 1, function() {
   notEqual(data.authenticity_token, 'cf50faa3fe97702ca1ae')
 })
 
+asyncTest('do not interact with contenteditable elements', 6, function() {
+  var contenteditable_div = $('#qunit-fixture').find('div')
+  contenteditable_div.append('<a href="http://www.shouldnevershowindocument.com" data-method="delete">')
+
+  var link = $('#edit-div').find('a')
+  link.triggerNative('click')
+
+  start()
+
+  collection = document.getElementsByTagName('form')
+  for (const item of collection) {
+    notEqual(item.action, "http://www.shouldnevershowindocument.com/")
+  }
+})
+
 })()

actionview/test/ujs/public/test/data-remote.js

@@ -41,6 +41,9 @@ module('data-remote', {
       }))
       .find('form').append($('<input type="text" name="user_name" value="john">'))
 
+    $('#qunit-fixture').append($('<div />', {
+      id: 'edit-div', 'contenteditable': 'true'
+    }))
   }
 })
 
@@ -508,4 +511,21 @@ asyncTest('inputs inside disabled fieldset are not submitted on remote forms', 3
     .triggerNative('submit')
 })
 
+asyncTest('clicking on a link with contenteditable attribute does not fire ajaxyness', 0, function() {
+  var contenteditable_div = $('#qunit-fixture').find('div')
+  var link = $('a[data-remote]')
+  contenteditable_div.append(link)
+
+  link
+    .bindNative('ajax:beforeSend', function() {
+      ok(false, 'ajax should not be triggered')
+    })
+    .bindNative('click', function(e) {
+      e.preventDefault()
+    })
+    .triggerNative('click')
+
+  setTimeout(function() { start() }, 20)
+})
+
 })()