VulnerabilityDeferred

CVE-2025-53479

The CheckUser extension’s Special:CheckUser interface is vulnerable to reflected XSS via the rev-deleted-user message.

MEDIUM 5.4EPSS 0.17%

Does this matter?

Lower severity and a low EPSS score (0.17%). Track it; it rarely justifies an emergency change on its own.

Description

The CheckUser extension’s Special:CheckUser interface is vulnerable to reflected XSS via the rev-deleted-user message. This message is rendered without proper escaping, making it possible to inject JavaScript through the uselang=x-xss language override mechanism. This issue affects Mediawiki - CheckUser extension: from 1.42.X before 1.42.7, from 1.43.X before 1.43.2.

CVSS 3.1: 5.4 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS: 0.17% probability · 7th percentile
CISA KEV: Not listed
Weakness: CWE-79
Source: c4f26cc8-17ff-4c99-b5e2-38fc1793eacc

References

https://gerrit.wikimedia.org/r/q/I159e14543912cb3bc7f4a00c3090c0285b154786
https://phabricator.wikimedia.org/T394693
https://phabricator.wikimedia.org/T394693

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.