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Regular expression Denial of Service in multiple packages

Moderate severity GitHub Reviewed Published Mar 31, 2021 in ckeditor/ckeditor5 • Updated Feb 1, 2023

Package

npm @ckeditor/ckeditor5-engine (npm)

Affected versions

<= 26.0.0

Patched versions

27.0.0
npm @ckeditor/ckeditor5-font (npm)
<= 26.0.0
27.0.0
npm @ckeditor/ckeditor5-image (npm)
<= 26.0.0
27.0.0
npm @ckeditor/ckeditor5-list (npm)
<= 26.0.0
27.0.0
npm @ckeditor/ckeditor5-markdown-gfm (npm)
<= 26.0.0
27.0.0
npm @ckeditor/ckeditor5-media-embed (npm)
<= 26.0.0
27.0.0
npm @ckeditor/ckeditor5-paste-from-office (npm)
<= 26.0.0
27.0.0
npm @ckeditor/ckeditor5-widget (npm)
<= 26.0.0
27.0.0

Description

Impact

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.

Patches

The problem has been recognized and patched. The fix will be available in version 27.0.0.

For more information

Email us at [email protected] if you have any questions or comments about this advisory.

Acknowledgements

The CKEditor 5 team would like to thank Yeting Li for recognizing and reporting these vulnerabilities.

References

@Mgsy Mgsy published to ckeditor/ckeditor5 Mar 31, 2021
Reviewed Mar 31, 2021
Published to the GitHub Advisory Database Apr 6, 2021
Published by the National Vulnerability Database Apr 29, 2021
Last updated Feb 1, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS score

0.481%
(76th percentile)

Weaknesses

CVE ID

CVE-2021-21391

GHSA ID

GHSA-3rh3-wfr4-76mj

Source code

No known source code
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