CVE-2025-53479

Public Exploit

CheckUser: Reflected Cross-Site Scripting (XSS) in Special:CheckUser via unsanitized internationalized message

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.

References

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

Frequently Asked Questions

What is the severity of CVE-2025-53479?: CVE-2025-53479 has been scored as a medium severity vulnerability.
How to fix CVE-2025-53479?: To fix CVE-2025-53479, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-53479 being actively exploited in the wild?: It is possible that CVE-2025-53479 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-53479?: CVE-2025-53479 affects Wikimedia Foundation Mediawiki - CheckUser extension.

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Description

Category

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

References

Frequently Asked Questions