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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.

PUBLISHED Reserved 2025-06-30 | Published 2025-07-08 | Updated 2025-07-10 | Assigner wikimedia-foundation

Problem types

CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')

Product status

Default status
unaffected

1.42.x (semver) before 1.42.7
affected

1.43.x (semver) before 1.43.2
affected

References

phabricator.wikimedia.org/T394693 exploit

phabricator.wikimedia.org/T394693

gerrit.wikimedia.org/...14543912cb3bc7f4a00c3090c0285b154786

cve.org (CVE-2025-53479)

nvd.nist.gov (CVE-2025-53479)

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