CVE-2025-53486: wikimedia foundation mediawiki - wikicategorytagcloud extension Cross-site Scripting

Vulnerability summary

CVE-2025-53486 is a medium (CVSS 5.4) Cross-site Scripting vulnerability in wikimedia foundation mediawiki - wikicategorytagcloud extension. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 20.2% of scored vulnerabilities.

Timeline

1. 07-07-2025
   PublishedVulnerability first disclosed.
2. 07-07-2025
   Last modifiedVulnerability information updated.

Description

The WikiCategoryTagCloud extension is vulnerable to reflected XSS via the linkstyle attribute, which is improperly concatenated into inline HTML without escaping. An attacker can inject JavaScript event handlers such as onmouseenter using carefully crafted input via the {{#tag:tagcloud}} parser function, resulting in arbitrary JavaScript execution when a victim hovers over a link in the category cloud. The vulnerability exists because the linkstyle parameter is only passed through Sanitizer::checkCss() (which does not escape HTML) and is then directly inserted into a style attribute using string concatenation instead of Html::element or Html::openElement. This issue affects Mediawiki - WikiCategoryTagCloud 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.

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.