CVE-2025-53370 is a high-severity (CVSS 8.6) Cross-site Scripting (XSS) vulnerability in starcitizentools/citizen-skin. A fix is available for starcitizentools/citizen-skin — see the affected versions and patch details below.
Citizen stored XSS vulnerability through short descriptions
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-53370.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
starcitizentools/citizen-skinReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Short descriptions set via the ShortDescription extension are inserted as raw HTML by the Citizen skin, allowing any user to insert arbitrary HTML into the DOM by editing a page.
Details
The shortdesc property, which contains unsanitized user input, is retrieved from the OutputPage and returned as the tagline:
https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/0d8a44011e02a081618359a1e90f462478e807aa/includes/Components/CitizenComponentPageHeading.php#L249-L251
The tagline is then provided to the template data:
https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/0d8a44011e02a081618359a1e90f462478e807aa/includes/Components/CitizenComponentPageHeading.php#L270-L275
The template then inserts the tagline into raw HTML without doing any escaping:
https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/0d8a44011e02a081618359a1e90f462478e807aa/templates/PageHeading.mustache#L12
PoC
- Enable Citizen and ShortDescription
- Add
{{SHORTDESC:<img src="" onerror="alert('citizen shortdescription xss')">}}to a page - Visit the page
Impact
Arbitrary HTML can be inserted into the DOM by any user, allowing for JavaScript to be executed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | starcitizentools/citizen-skin | ≥ 1.9.4&&< 3.4.0 | 3.4.0composer require starcitizentools/citizen-skin:^3.4.0 |
Affected Products
citizenstarcitizen.toolsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for starcitizentools/citizen-skin, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update starcitizentools/citizen-skin to 3.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-53370 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2025-53370 in your dependencies?
Find it across Packagist, including transitive dependencies.