GitStock

ckeditor/ckeditor5 · Security

CKEditor 5 Markdown plugin Regular expression Denial of Service

GHSA ID
GHSA-hgmg-hhc8-g5wr
CVE ID
CVE-2021-21254
Severity
medium
Published
Updated
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v3
6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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.

CWEs

  • CWE-400 · Uncontrolled Resource Consumption

References

Open GitHub