CVE-2025-53480 Cross-site scripting in Mediawiki - CheckUser extension
Attackers can execute arbitrary scripts in victims' browsers via unsanitized internationalization messages in the CheckUser extension's Investigate page.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2025-53480?
CVE-2025-53480 is a medium-severity cross-site scripting vulnerability in Wikimedia Foundation Mediawiki - CheckUser extension, published on 8 Jul 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
The CheckUser extension’s Special:Investigate page has a vulnerability in the Account information tab, where specific internationalized messages are rendered without proper escaping. Attackers can exploit this by appending ?uselang=x-xss to the URL, causing reflected XSS when the UI renders affected message keys.
This issue affects Mediawiki - CheckUser extension: from 1.39.X before 1.39.13, from 1.42.X before 1.42.7, from 1.43.X before 1.43.2.
Weakness: CWE-79
Which versions are affected by CVE-2025-53480?
How do I fix CVE-2025-53480?
No fix has been published for CVE-2025-53480 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2025-53480 being exploited?
There is no known exploitation of CVE-2025-53480 in the wild and no public exploit code.
Sources
Also known as GHSA-66x3-m6h7-8jgc.