CVE-2021-31553

MEDIUM

MediaWiki < 1.35.2 - Denial of Service via CheckUser Extension Username Handling

Title source: llm

Description

An issue was discovered in the CheckUser extension for MediaWiki through 1.35.2. MediaWiki usernames with trailing whitespace could be stored in the cu_log database table such that denial of service occurred for certain CheckUser extension pages and functionality. For example, the attacker could turn off Special:CheckUserLog and thus interfere with usage tracking.

References (7)

Core 7

Core References

Third Party Advisory x_refsource_misc

https://phabricator.wikimedia.org/T275669

Issue Tracking, Third Party Advisory x_refsource_misc

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667023

Issue Tracking, Third Party Advisory x_refsource_misc

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667024

Issue Tracking, Third Party Advisory x_refsource_misc

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667025

Issue Tracking, Third Party Advisory x_refsource_misc

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/667027

Issue Tracking, Third Party Advisory x_refsource_misc

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666963

Issue Tracking, Third Party Advisory x_refsource_misc

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CheckUser/+/666964

Scores

CVSS v3 6.5

EPSS 0.0140

EPSS Percentile 68.9%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Details

CWE

CWE-428

Status published

Products (1)

mediawiki/mediawiki < 1.35.2

Published Apr 22, 2021

Tracked Since Feb 18, 2026