An XSS vulnerability was discovered in the Flash fallback files in MediaElement, a library that is included with WordPress. Because the Flash files are no longer needed for most use cases, they have been removed from WordPress.
MediaElement has released a new version that contains a fix for the bug, and a WordPress plugin containing the fixed files is available in the plugin repository.
Thank you to the reporters of this issue for practicing responsible security disclosure: Enguerran Gillier and Widiz.
21 other bugs were fixed in WordPress 4.9.2. Particularly of note were:
- The previous taxonomy-agnostic behavior of
- Switching themes will now attempt to restore previous widget assignments, even when there are no sidebars to map.
The Codex has more information about all of the issues fixed in 4.9.2, if you’d like to learn more.
Download WordPress 4.9.2 or venture over to Dashboard ? Updates and click “Update Now.” Sites that support automatic background updates are already beginning to update automatically.