CVE-2025-53478 CheckUser: Reflected Cross-Site Scripting (XSS) in Special:Investigate via unsanitized i18n messages
Reflected XSS in MediaWiki CheckUser extension allows attackers to execute scripts via unsanitized i18n messages on the 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-2025-53478?
CVE-2025-53478 is a medium-severity cross-site scripting vulnerability in Wikimedia Foundation Mediawiki - CheckUser extension, published on 7 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 interface is vulnerable to reflected XSS due to improper escaping of certain internationalized system messages rendered on the “IPs and User agents” tab.
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-2025-53478?
How do I fix CVE-2025-53478?
No fix has been published for CVE-2025-53478 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-2025-53478 being exploited?
There is no known exploitation of CVE-2025-53478 in the wild and no public exploit code.
Sources
Also known as GHSA-r979-wmj9-cr9m.