diff --git a/lib/htmlpurifier/readme_moodle.txt b/lib/htmlpurifier/readme_moodle.txt
index 89ba310d8fd..43c714b177a 100644
--- a/lib/htmlpurifier/readme_moodle.txt
+++ b/lib/htmlpurifier/readme_moodle.txt
@@ -1,4 +1,4 @@
-Description of HTML Purifier v4.8.0 library import into Moodle
+Description of HTML Purifier v4.9.3 library import into Moodle
 
 * Make new (or delete contents of) /lib/htmlpurifier/
 * Copy everything from /library/ folder to /lib/htmlpurifier/
diff --git a/lib/tests/htmlpurifier_test.php b/lib/tests/htmlpurifier_test.php
index 7d7c87aec43..f7d5679462e 100644
--- a/lib/tests/htmlpurifier_test.php
+++ b/lib/tests/htmlpurifier_test.php
@@ -44,7 +44,7 @@ class core_htmlpurifier_testcase extends basic_testcase {
         // Also note we do not need to test links with an existing rel attribute as the HTML Purifier is configured to remove
         // the rel attribute.
         $text = '<a href="http://moodle.org" target="_blank">Some link</a>';
-        $expected = '<a href="http://moodle.org" target="_blank" rel="noreferrer">Some link</a>';
+        $expected = '<a href="http://moodle.org" target="_blank" rel="noreferrer noopener">Some link</a>';
         $result = format_text($text, FORMAT_HTML);
         $this->assertSame($expected, $result);
 
diff --git a/lib/thirdpartylibs.xml b/lib/thirdpartylibs.xml
index 71400eaf826..08ba6b555ed 100644
--- a/lib/thirdpartylibs.xml
+++ b/lib/thirdpartylibs.xml
@@ -46,7 +46,7 @@
     <location>htmlpurifier</location>
     <name>HTML Purifier</name>
     <license>LGPL</license>
-    <version>4.8.0</version>
+    <version>4.9.3</version>
     <licenseversion>2.1+</licenseversion>
   </library>
   <library>