diff --git a/Doxyfile b/Doxyfile
index 7d01f31d..51d1fee4 100644
--- a/Doxyfile
+++ b/Doxyfile
@@ -31,7 +31,7 @@ PROJECT_NAME           = HTMLPurifier
 # This could be handy for archiving the generated documentation or
 # if some version control system is used.
 
-PROJECT_NUMBER         = 4.14.0
+PROJECT_NUMBER         = 4.15.0
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute)
 # base path where the generated documentation will be put.
diff --git a/NEWS b/NEWS
index 92c87218..a1c98844 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,15 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
     . Internal change
 ==========================
 
+4.15.0, released 2022-09-18
+! PHP 8.1 and 8.2 support, esp. fixes for deprecation warnings.  A joint effort
+  by David Rans, Tim Düsterhus, Kieran and John Flatness.
+! Allow contenteditable="false" (#336), contributed by Kieran.
+- Replace PHP 8.1 deprecated utf8_ functions with mbstring (#326),
+  contributed by John Flatness.
+- Enhanced composer suggestions with extensions (#317), contributed by
+  func0der.
+
 4.14.0, released 2021-12-24
 ! Add "background-size" support (#289), contributed by Václav Smítal
 ! Transform deprecated width attribute when tidying HTML, contributed by
diff --git a/VERSION b/VERSION
index 09ce0ce7..f029ee57 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.14.0
\ No newline at end of file
+4.15.0
\ No newline at end of file
diff --git a/WHATSNEW b/WHATSNEW
index 4d5e9291..32403eb2 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -1,4 +1,3 @@
-HTML Purifier 4.14.x is a maintenance release which improves
-PHP7 and PHP8 compatibility.  There are also some minor new features
-(background-size) and some miscellaneous fixes to remove notices
-from recent versions of PHP.
+HTML Purifier 4.15.x is a maintenance release which improves
+compatibility with PHP8.2.  There is also support for
+contenteditable="false" added.
diff --git a/configdoc/usage.xml b/configdoc/usage.xml
index c0df5aba..9767c7af 100644
--- a/configdoc/usage.xml
+++ b/configdoc/usage.xml
@@ -5,8 +5,8 @@
    <line>162</line>
   </file>
   <file name="HTMLPurifier/Lexer.php">
-   <line>85</line>
-   <line>326</line>
+   <line>90</line>
+   <line>331</line>
   </file>
   <file name="HTMLPurifier/Lexer/DirectLex.php">
    <line>67</line>
@@ -124,7 +124,7 @@
    <line>122</line>
   </file>
   <file name="HTMLPurifier/Lexer.php">
-   <line>308</line>
+   <line>313</line>
   </file>
  </directive>
  <directive id="Output.Newline">
@@ -172,8 +172,11 @@
    <line>234</line>
   </file>
   <file name="HTMLPurifier/Lexer.php">
-   <line>313</line>
-   <line>353</line>
+   <line>318</line>
+   <line>358</line>
+  </file>
+  <file name="HTMLPurifier/AttrDef/HTML/ContentEditable.php">
+   <line>8</line>
   </file>
   <file name="HTMLPurifier/HTMLModule/Image.php">
    <line>37</line>
@@ -250,12 +253,12 @@
  </directive>
  <directive id="Core.LexerImpl">
   <file name="HTMLPurifier/Lexer.php">
-   <line>80</line>
+   <line>85</line>
   </file>
  </directive>
  <directive id="Core.MaintainLineNumbers">
   <file name="HTMLPurifier/Lexer.php">
-   <line>84</line>
+   <line>89</line>
   </file>
   <file name="HTMLPurifier/Lexer/DirectLex.php">
    <line>62</line>
@@ -263,23 +266,23 @@
  </directive>
  <directive id="Core.LegacyEntityDecoder">
   <file name="HTMLPurifier/Lexer.php">
-   <line>215</line>
-   <line>337</line>
+   <line>220</line>
+   <line>342</line>
   </file>
  </directive>
  <directive id="Core.ConvertDocumentToFragment">
   <file name="HTMLPurifier/Lexer.php">
-   <line>324</line>
+   <line>329</line>
   </file>
  </directive>
  <directive id="Core.RemoveProcessingInstructions">
   <file name="HTMLPurifier/Lexer.php">
-   <line>347</line>
+   <line>352</line>
   </file>
  </directive>
  <directive id="Core.HiddenElements">
   <file name="HTMLPurifier/Lexer.php">
-   <line>351</line>
+   <line>356</line>
   </file>
   <file name="HTMLPurifier/Strategy/RemoveForeignElements.php">
    <line>36</line>
@@ -287,12 +290,12 @@
  </directive>
  <directive id="Core.AggressivelyRemoveScript">
   <file name="HTMLPurifier/Lexer.php">
-   <line>352</line>
+   <line>357</line>
   </file>
  </directive>
  <directive id="Core.RemoveScriptContents">
   <file name="HTMLPurifier/Lexer.php">
-   <line>353</line>
+   <line>358</line>
   </file>
   <file name="HTMLPurifier/Strategy/RemoveForeignElements.php">
    <line>35</line>
@@ -451,7 +454,7 @@
  </directive>
  <directive id="HTML.FlashAllowFullScreen">
   <file name="HTMLPurifier/AttrTransform/SafeParam.php">
-   <line>53</line>
+   <line>58</line>
   </file>
  </directive>
  <directive id="Cache.SerializerPath">
diff --git a/library/HTMLPurifier.includes.php b/library/HTMLPurifier.includes.php
index ee81cac6..47ee0133 100644
--- a/library/HTMLPurifier.includes.php
+++ b/library/HTMLPurifier.includes.php
@@ -7,7 +7,7 @@
  * primary concern and you are using an opcode cache. PLEASE DO NOT EDIT THIS
  * FILE, changes will be overwritten the next time the script is run.
  *
- * @version 4.14.0
+ * @version 4.15.0
  *
  * @warning
  *      You must *not* include any other HTML Purifier files before this file,
@@ -107,6 +107,7 @@ require 'HTMLPurifier/AttrDef/HTML/Bool.php';
 require 'HTMLPurifier/AttrDef/HTML/Nmtokens.php';
 require 'HTMLPurifier/AttrDef/HTML/Class.php';
 require 'HTMLPurifier/AttrDef/HTML/Color.php';
+require 'HTMLPurifier/AttrDef/HTML/ContentEditable.php';
 require 'HTMLPurifier/AttrDef/HTML/FrameTarget.php';
 require 'HTMLPurifier/AttrDef/HTML/ID.php';
 require 'HTMLPurifier/AttrDef/HTML/Pixels.php';
diff --git a/library/HTMLPurifier.php b/library/HTMLPurifier.php
index 2177fc85..26f06127 100644
--- a/library/HTMLPurifier.php
+++ b/library/HTMLPurifier.php
@@ -19,7 +19,7 @@
  */
 
 /*
-    HTML Purifier 4.14.0 - Standards Compliant HTML Filtering
+    HTML Purifier 4.15.0 - Standards Compliant HTML Filtering
     Copyright (C) 2006-2008 Edward Z. Yang
 
     This library is free software; you can redistribute it and/or
@@ -58,12 +58,12 @@ class HTMLPurifier
      * Version of HTML Purifier.
      * @type string
      */
-    public $version = '4.14.0';
+    public $version = '4.15.0';
 
     /**
      * Constant with version of HTML Purifier.
      */
-    const VERSION = '4.14.0';
+    const VERSION = '4.15.0';
 
     /**
      * Global configuration object.
diff --git a/library/HTMLPurifier.safe-includes.php b/library/HTMLPurifier.safe-includes.php
index a3261f8a..94543f59 100644
--- a/library/HTMLPurifier.safe-includes.php
+++ b/library/HTMLPurifier.safe-includes.php
@@ -101,6 +101,7 @@ require_once $__dir . '/HTMLPurifier/AttrDef/HTML/Bool.php';
 require_once $__dir . '/HTMLPurifier/AttrDef/HTML/Nmtokens.php';
 require_once $__dir . '/HTMLPurifier/AttrDef/HTML/Class.php';
 require_once $__dir . '/HTMLPurifier/AttrDef/HTML/Color.php';
+require_once $__dir . '/HTMLPurifier/AttrDef/HTML/ContentEditable.php';
 require_once $__dir . '/HTMLPurifier/AttrDef/HTML/FrameTarget.php';
 require_once $__dir . '/HTMLPurifier/AttrDef/HTML/ID.php';
 require_once $__dir . '/HTMLPurifier/AttrDef/HTML/Pixels.php';
diff --git a/library/HTMLPurifier/Config.php b/library/HTMLPurifier/Config.php
index 16a6b322..797d2687 100644
--- a/library/HTMLPurifier/Config.php
+++ b/library/HTMLPurifier/Config.php
@@ -21,7 +21,7 @@ class HTMLPurifier_Config
      * HTML Purifier's version
      * @type string
      */
-    public $version = '4.14.0';
+    public $version = '4.15.0';
 
     /**
      * Whether or not to automatically finalize