CVE-2025-61651: Mediawiki Checkuser

Medium severity, CVSS 6.1. EPSS: 0.2% chance of exploitation in the next 30 days.

Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation CheckUser. This vulnerability is associated with program files modules/ext.CheckUser/checkuser/checkUserHelper/buildUserElement.Js. This issue affects CheckUser: from * before 1.44.1.

Affected products

• Mediawiki Checkuser: before 1.44.1 (fixed in 1.44.1)

Published 2026-02-03. Last modified 2026-06-17.