CVE-2025-53495 is a Missing Authorization vulnerability (CWE-862) identified in the AbuseFilter extension of the Wikimedia Foundation's Mediawiki software. The affected versions include 1.39.x prior to 1.39.13, 1.42.x prior to 1.42.7, and 1.43.x prior to 1.43.2. AbuseFilter is a Mediawiki extension used to detect and prevent disruptive edits or abusive behavior on wiki platforms by applying customizable filtering rules. The vulnerability arises because the extension fails to properly enforce authorization checks before allowing access to certain AbuseFilter functionalities. This missing authorization means that unauthorized users could potentially access or manipulate AbuseFilter features that should be restricted, such as creating, modifying, or bypassing filters designed to prevent abuse. Although no known exploits are currently reported in the wild, the flaw could allow attackers to circumvent content moderation controls, leading to unauthorized content changes, disruption of wiki operations, or evasion of abuse detection mechanisms. The absence of a CVSS score indicates that the vulnerability has not yet been fully assessed for severity, but the nature of missing authorization in a widely used content management extension suggests a significant risk if exploited. The vulnerability affects multiple recent versions of Mediawiki, a popular open-source platform powering many public and private wikis worldwide, including those used by organizations for knowledge management and collaboration.

For European organizations using Mediawiki with the AbuseFilter extension, this vulnerability poses a risk to the integrity and availability of wiki content and collaboration environments. Unauthorized users could exploit the missing authorization to bypass abuse filters, potentially injecting malicious or disruptive content, deleting or altering critical information, or disabling abuse prevention mechanisms. This could lead to misinformation, loss of trust in internal knowledge bases, operational disruption, and increased administrative overhead to detect and remediate abuse. Public-facing wikis operated by European institutions or companies could suffer reputational damage if attackers manipulate content or vandalize pages. Additionally, organizations relying on Mediawiki for sensitive or regulated information could face compliance risks if unauthorized changes go undetected. The impact is heightened in environments where AbuseFilter is a key control for maintaining content quality and security. Since Mediawiki is widely used across Europe in both public sector and private enterprises, the vulnerability could affect a broad range of sectors including government, education, research, and corporate knowledge management.

European organizations should prioritize upgrading the AbuseFilter extension to the fixed versions: 1.39.13 or later for the 1.39.x branch, 1.42.7 or later for the 1.42.x branch, and 1.43.2 or later for the 1.43.x branch. Until patches are applied, administrators should review and tighten access controls around AbuseFilter management interfaces, ensuring only trusted and authenticated users have permissions to modify filters. Implementing additional monitoring and alerting on AbuseFilter configuration changes can help detect unauthorized activity early. Organizations should audit current AbuseFilter rules and logs to identify any suspicious changes or bypass attempts. Where possible, isolate Mediawiki instances behind strong authentication and network segmentation to reduce exposure to unauthorized users. Regular backups of wiki content and configurations will aid recovery if abuse occurs. Finally, organizations should stay informed of updates from the Wikimedia Foundation and community regarding this vulnerability and any emerging exploits.