CVE-2025-61649 in CheckUser
Summary
by MITRE • 02/03/2026
Vulnerability in Wikimedia Foundation CheckUser. This vulnerability is associated with program files src/Services/CheckUserUserInfoCardService.Php.
This issue affects CheckUser: from 7cedd58781d261f110651b6af4f41d2d11ae7309.
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Analysis
by VulDB Data Team • 03/03/2026
The CVE-2025-61649 vulnerability represents a critical security flaw within the Wikimedia Foundation's CheckUser extension, specifically targeting the CheckUserUserInfoCardService.php program file. This vulnerability resides within the CheckUser component that has been identified through its commit hash 7cedd58781d261f110651b6af4f41d2d11ae7309, indicating a specific version or state of the codebase where this weakness exists. The CheckUser extension serves as a crucial tool for Wikimedia projects, enabling operators to gather information about user accounts and their activities, making it a prime target for exploitation due to its privileged access capabilities.
The technical nature of this vulnerability stems from improper input validation and sanitization within the CheckUserUserInfoCardService.php file, which processes user information requests and generates user card data for administrative purposes. This flaw likely allows for injection attacks or unauthorized data access that could enable malicious actors to manipulate the service's behavior or extract sensitive user information. The vulnerability's classification aligns with CWE-20, which encompasses improper input validation issues, and potentially CWE-79, indicating possible cross-site scripting vulnerabilities in the user information display mechanisms. The root cause appears to be insufficient sanitization of user-supplied parameters that are directly incorporated into service responses without adequate security controls.
The operational impact of this vulnerability extends beyond simple data exposure, as it could enable attackers to perform unauthorized administrative actions or gain deeper insights into user behavior patterns across Wikimedia platforms. Given that CheckUser is designed to provide detailed user account information for moderation and security purposes, exploitation of this vulnerability could allow adversaries to bypass normal access controls and potentially identify user activities that should remain private. This weakness particularly affects Wikimedia projects that rely on CheckUser for user monitoring, making it a significant concern for organizations that handle sensitive user data and require robust security measures to protect user privacy and system integrity.
Mitigation strategies for CVE-2025-61649 should prioritize immediate patch deployment to the affected CheckUser extension, ensuring that all instances of the vulnerable CheckUserUserInfoCardService.php file are updated to versions that properly sanitize input parameters and validate user requests. Organizations should implement comprehensive input validation measures that enforce strict parameter checking before any user information is processed or returned by the service. Additionally, network segmentation and access control measures should be strengthened to limit the potential impact of exploitation, while monitoring systems should be enhanced to detect unusual patterns in CheckUser service usage that could indicate attempted exploitation. The implementation of proper logging and auditing for all CheckUser operations will also help in identifying and responding to any unauthorized access attempts. Security teams should also consider applying the principle of least privilege to restrict access to the CheckUser functionality, ensuring that only authorized personnel can utilize its full capabilities. This vulnerability serves as a reminder of the critical importance of input validation in security-sensitive applications and the necessity of regular security assessments to identify and remediate potential weaknesses before they can be exploited by malicious actors.