CVE-2023-45362 in MediaWiki
Summary
by MITRE • 11/03/2023
An issue was discovered in DifferenceEngine.php in MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. diff-multi-sameuser (aka "X intermediate revisions by the same user not shown") ignores username suppression. This is an information leak.
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Analysis
by VulDB Data Team • 02/09/2026
The vulnerability identified as CVE-2023-45362 affects MediaWiki's DifferenceEngine.php component and represents a significant information disclosure issue that impacts versions prior to specific security patches. This flaw resides in the handling of diff-multi-sameuser functionality, which is designed to display multiple revisions by the same user in a compact format. The vulnerability occurs when the system processes revision histories where multiple edits are made by identical usernames, failing to properly suppress or anonymize user identities in certain contexts.
The technical implementation flaw stems from the DifferenceEngine.php module not adequately enforcing username suppression mechanisms when displaying multiple revisions by the same user. This creates a scenario where sensitive information about user activities can be inadvertently exposed through the revision history interface. The vulnerability specifically affects the diff-multi-sameuser feature, commonly referred to as "X intermediate revisions by the same user not shown," which is intended to optimize display by grouping consecutive edits from the same user. However, the implementation fails to properly sanitize or suppress usernames when these grouped revisions are rendered in the user interface.
This information leak represents a serious operational impact for MediaWiki deployments, particularly those hosting sensitive content or operating in environments where user privacy is paramount. The exposure of username information through revision history can potentially reveal user behavior patterns, collaboration dynamics, and access patterns that might not be otherwise visible. Attackers could exploit this vulnerability to identify users who have made specific edits to particular pages, potentially enabling social engineering attacks or targeted reconnaissance activities. The vulnerability affects a wide range of MediaWiki versions, including major release branches, making it particularly concerning for organizations with extensive MediaWiki installations.
The security implications align with CWE-200 (Information Exposure) and can be mapped to ATT&CK technique T1082 (System Information Discovery) and T1566 (Phishing with Social Engineering) within the MITRE ATT&CK framework. Organizations utilizing MediaWiki for content management, documentation systems, or collaborative platforms face significant risks from this vulnerability. The information disclosure occurs at the application layer through the web interface, making it accessible to any user with appropriate privileges to view revision history. This vulnerability particularly impacts deployments where user privacy is critical, such as healthcare systems, government portals, or corporate documentation platforms where revision tracking might reveal confidential user activities.
Mitigation strategies include applying the relevant security patches for MediaWiki versions 1.35.12, 1.39.5, and 1.40.1 respectively, or upgrading to supported versions that contain the fix for this username suppression issue. Administrators should also consider implementing additional access controls and monitoring for revision history access patterns. The patch addresses the core issue by ensuring proper username suppression in the diff-multi-sameuser functionality, maintaining the intended privacy protections while preserving the utility of the revision history display feature. Organizations should conduct thorough testing of the patched versions to ensure compatibility with existing MediaWiki configurations and extensions before deployment.