In affected versions of @ckeditor/ckeditor5-markdown-gfm a regular expression denial of service (ReDoS) vulnerability has been discovered.

Impact

The vulnerability allowed to abuse a link recognition regular expression, which could cause a significant performance drop resulting in a browser tab freeze. It affects all users using the CKEditor 5 Markdown plugin at version <= 24.0.0.

Workarounds

• Disabling the Markdown plugin.

Upgrade to version 25.0.0 or later