GHSA-hgmg-hhc8-g5wr CKEditor 5 Markdown plugin Regular expression Denial of Service

• npm @ckeditor/ckeditor5-markdown-gfm: < 25.0.0 → fixed in 25.0.0

Impact A regular expression denial of service (ReDoS) vulnerability has been discovered in the CKEditor 5 Markdown plugin code. 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. Patches The problem has been recognized and patched. The fix will be available in version 25.0.0. Workarounds The user can work around the issue by: • Upgrading CKEditor 5 to version 25.0.0. • Disabling the Markdown plugin. More information If you have any questions or comments about this advisory: • Email us at [email protected] Acknowledgements The CKEditor 5 team would like to thank Erik Krogh Kristensen from the GitHub team for recognizing this vulnerability and Alvaro Muñoz from GitHub for reporting it.