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Regular expression Denial of Service in Markdown plugin

Low
Mgsy published GHSA-hgmg-hhc8-g5wr Jan 28, 2021

Package

npm @ckeditor/ckeditor5-markdown-gfm (npm)

Affected versions

<= 24.0.0

Patched versions

25.0.0

Description

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:

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.

Severity

Low

CVE ID

CVE-2021-21254

Weaknesses

No CWEs