CVE-2025-53369

Short descriptions are not properly sanitized by the ShortDescription before being inserted as HTML using mw.util.addSubtitle, allowing any user to insert arbitrary HTML into the DOM by editing a page.

Details

The description provided by the user via the {{SHORTDESC:}} parser function is insufficiently sanitized by the sanitize() function, as html entities are decoded:
https://github.com/StarCitizenTools/mediawiki-extensions-ShortDescription/blob/7244b1e8b5cb6dbd7e546c5be7fed8a56e33d065/includes/Hooks/ParserHooks.php#L147-L159
Via JS, the short description is then passed to mw.util.addSubtitle, which inserts it as raw HTML:
https://github.com/StarCitizenTools/mediawiki-extensions-ShortDescription/blob/7244b1e8b5cb6dbd7e546c5be7fed8a56e33d065/modules/ext.shortDescription.js#L8
https://github.com/wikimedia/mediawiki/blob/96372101b3c579d9992e8a31a3ccd90a937cac47/resources/src/mediawiki.util/util.js#L552-L563

PoC

1. Enable ShortDescription
2. Make sure $wgShortDescriptionEnableTagline is set to true (this is the default)
3. Create a page and insert the following wikitext: {{SHORTDESC:<img src="" onerror="alert('shortdescription xss')">}}
4. Visit the page

Arbitrary HTML can be inserted into the DOM by any user, allowing for JavaScript to be executed.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2025-53369 has a CVSS score of 8.6 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.0.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-53369? CVE-2025-53369 is a high-severity cross-site scripting (XSS) vulnerability in starcitizentools/short-description (composer), affecting versions >= 4.0.0, < 4.0.1. It is fixed in 4.0.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-53369? CVE-2025-53369 has a CVSS score of 8.6 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of starcitizentools/short-description are affected by CVE-2025-53369? starcitizentools/short-description (composer) versions >= 4.0.0, < 4.0.1 is affected.
4. Is there a fix for CVE-2025-53369? Yes. CVE-2025-53369 is fixed in 4.0.1. Upgrade to this version or later.
5. Is CVE-2025-53369 exploitable, and should I be worried? Whether CVE-2025-53369 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-53369 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-53369? Upgrade starcitizentools/short-description to 4.0.1 or later.