Ecosyste.ms: Advisories

Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLWhnbWctaGhjOC1nNXdy

CKEditor 5 Markdown plugin Regular expression Denial of Service

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.

Permalink: https://github.com/advisories/GHSA-hgmg-hhc8-g5wr
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLWhnbWctaGhjOC1nNXdy
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: about 3 years ago
Updated: about 1 year ago

CVSS Score: 6.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Identifiers: GHSA-hgmg-hhc8-g5wr, CVE-2021-21254
References:

• https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-hgmg-hhc8-g5wr
• https://github.com/ckeditor/ckeditor5/releases/tag/v25.0.0
• https://www.npmjs.com/package/@ckeditor/ckeditor5-markdown-gfm
• https://nvd.nist.gov/vuln/detail/CVE-2021-21254
• https://github.com/advisories/GHSA-hgmg-hhc8-g5wr

Repository: https://github.com/ckeditor/ckeditor5
Blast Radius: 15.7

Affected Packages