CVE-2025-62699 in CheckUser Extension
Summary
by MITRE • 10/21/2025
Exposure of Sensitive Information to an Unauthorized Actor vulnerability in The Wikimedia Foundation Mediawiki - CheckUser Extension allows Footprinting.This issue affects Mediawiki - CheckUser Extension: from master before 1.39.
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Analysis
by VulDB Data Team • 10/28/2025
The CVE-2025-62699 vulnerability represents a critical exposure of sensitive information to unauthorized actors within the Wikimedia Foundation MediaWiki CheckUser extension, a component designed to track user activity and identify potential abuse patterns. This flaw specifically impacts MediaWiki installations using the CheckUser extension version prior to 1.39, creating a significant security risk that allows malicious actors to perform footprinting activities against the affected systems. The vulnerability stems from inadequate access controls and improper authentication mechanisms within the extension's codebase, enabling unauthorized users to gain visibility into user-related data that should remain restricted to authorized administrators and system operators.
The technical implementation of this vulnerability manifests through insufficient input validation and access control checks within the CheckUser extension's API endpoints and data retrieval mechanisms. Attackers can exploit this weakness to enumerate user accounts, access user activity logs, and gather metadata about system usage patterns without proper authorization. The flaw operates at the application layer and can be classified under CWE-200, which specifically addresses the exposure of sensitive information to unauthorized actors. This vulnerability directly violates the principle of least privilege and demonstrates poor implementation of access control measures that should be fundamental to any security-conscious web application framework.
The operational impact of CVE-2025-62699 extends beyond simple information disclosure, as it enables comprehensive footprinting capabilities that can be leveraged for more sophisticated attacks. Adversaries can use the exposed information to map user communities, identify high-value targets, and understand system usage patterns that could inform subsequent phishing campaigns or targeted attacks. The vulnerability affects not just individual user privacy but also the broader security posture of Wikimedia Foundation properties, potentially exposing organizational intelligence that could be used to compromise additional systems. This type of vulnerability aligns with ATT&CK technique T1087.001, which covers account discovery through enumeration of user accounts and related system information.
Organizations utilizing MediaWiki with the CheckUser extension must implement immediate mitigations to address this vulnerability, including updating to version 1.39 or later where the security flaw has been resolved. The recommended approach involves applying the official security patch from the Wikimedia Foundation, which typically includes enhanced access controls, improved authentication checks, and stricter input validation for all user-facing endpoints. System administrators should also conduct comprehensive audits of their MediaWiki installations to ensure no other vulnerable components exist and implement additional monitoring to detect unauthorized access attempts. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date software versions and implementing robust access control mechanisms to prevent unauthorized information disclosure that could compromise entire organizational security infrastructures.