# 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.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **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 available:** No
- **Published:** 8 Jul 2025
- **Updated:** 8 Jul 2025
- **Also known as:** GHSA-66x3-m6h7-8jgc

## 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 (Improper Neutralization of Input During Web Page Generation)

## 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.

## Is CVE-2025-53480 being exploited?

There is no known exploitation of CVE-2025-53480 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-53480 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-53480 in the wild and no public exploit code.

Affected product: Wikimedia Foundation Mediawiki - CheckUser extension. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-53480/ (Markdown: https://insights.sbomify.com/CVE-2025-53480/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-53480
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-53480
- OSV: https://osv.dev/vulnerability/CVE-2025-53480

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-53480/
Summaries are generated and may contain mistakes; the official description above is the record.