Wikimedia CheckUser up to 1.44.0 buildUserElement.Js cross site scripting

Summaryinfo

A vulnerability labeled as problematic has been found in Wikimedia CheckUser up to 1.44.0. Affected is an unknown function of the file modules/ext.CheckUser/checkuser/checkUserHelper/buildUserElement.Js. Such manipulation leads to cross site scripting. This vulnerability is uniquely identified as CVE-2025-61651. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Wikimedia CheckUser up to 1.44.0. Affected by this issue is an unknown part of the file modules/ext.CheckUser/checkuser/checkUserHelper/buildUserElement.Js. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. 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. Impacted is integrity. CVE summarizes:

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.

The advisory is shared for download at phabricator.wikimedia.org. This vulnerability is handled as CVE-2025-61651 since 09/29/2025. The exploitation is known to be easy. The attack may be launched remotely. Additional levels of successful authentication are required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 1.44.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-206637). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Content Management System

Vendor

• Wikimedia

Name

• CheckUser

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.35
• 1.36
• 1.37
• 1.38
• 1.39
• 1.40
• 1.41
• 1.42
• 1.43
• 1.44.0

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion