medium
6.5
CWE
400
Advisory Published
Updated

CVE-2021-21391: Regular expression Denial of Service in multiple packages

First published: Thu Apr 29 2021(Updated: )

CKEditor 5 provides a WYSIWYG editing solution. This CVE affects the following npm packages: ckeditor5-engine, ckeditor5-font, ckeditor5-image, ckeditor5-list, ckeditor5-markdown-gfm, ckeditor5-media-embed, ckeditor5-paste-from-office, and ckeditor5-widget. Following an internal audit, a regular expression denial of service (ReDoS) vulnerability has been discovered in multiple CKEditor 5 packages. The vulnerability allowed to abuse particular regular expressions, which could cause a significant performance drop resulting in a browser tab freeze. It affects all users using the CKEditor 5 packages listed above at version <= 26.0.0. The problem has been recognized and patched. The fix will be available in version 27.0.0.

Credit: security-advisories@github.com

Affected SoftwareAffected VersionHow to fix
Ckeditor Ckeditor5-engine<27.0.0
Ckeditor Ckeditor5-font<27.0.0
Ckeditor Ckeditor5-image<27.0.0
Ckeditor Ckeditor5-list<27.0.0
Ckeditor Ckeditor5-markdown-gfm<27.0.0
Ckeditor Ckeditor5-media-embed<27.0.0
Ckeditor Ckeditor5-paste-from-office<27.0.0
Ckeditor Ckeditor5-widget<27.0.0

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Reference Links

Frequently Asked Questions

  • What is CVE-2021-21391?

    CVE-2021-21391 is a vulnerability in CKEditor 5 npm packages that allows arbitrary code execution.

  • Which npm packages are affected by CVE-2021-21391?

    The following npm packages are affected: ckeditor5-engine, ckeditor5-font, ckeditor5-image, ckeditor5-list, ckeditor5-markdown-gfm, ckeditor5-media-embed, ckeditor5-paste-from-office, and ckeditor5-widget.

  • What is the severity of CVE-2021-21391?

    The severity of CVE-2021-21391 is medium, with a CVSS score of 6.5.

  • How can I fix CVE-2021-21391?

    To fix CVE-2021-21391, update the affected CKEditor 5 npm packages to a version higher than 27.0.0.

  • Where can I find more information about CVE-2021-21391?

    You can find more information about CVE-2021-21391 in the following references: [GitHub Advisory](https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-3rh3-wfr4-76mj) and [NPM Package](https://www.npmjs.com/package/@ckeditor/ckeditor5-engine).

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