On 16 January, 2018, WordPress 4.0.22 was released to the public.
Installation/Update Information
To download WordPress 4.0.22, update automatically from the Dashboard > Updates menu in your site’s admin area or visit https://wordpress.org/download/release-archive/.
For step-by-step instructions on installing and updating WordPress:
If you are new to WordPress, we recommend that you begin with the following:
- New To WordPress – Where to Start
- First Steps With WordPress or Upgrading WordPress Extended
- WordPress Lessons
Summary
From the WordPress 4.9.2 release post: WordPress versions 4.9 and earlier are affected by an XSS vulnerability in the Flash fallback files in MediaElement 4.x. The following fixes have been implemented in this release:
- Upgrade: When deleting old files, if deletion fails attempt to empty the file instead. (#42963)
- External Libraries: Remove unnecessary / obsoleted MediaElement.js files. (#42720)
List of Files Revised
wp-admin/includes/update-core.php wp-admin/about.php wp-includes/js/mediaelement/flashmediaelement.swf wp-includes/js/mediaelement/silverlightmediaelement.xap wp-includes/version.php