CVE-2025-53487 in ApprovedRevs Extension
Summary
by MITRE • 07/07/2025
The ApprovedRevs extension for MediaWiki is vulnerable to stored XSS in multiple locations where system messages are inserted into raw HTML without proper escaping. Attackers can exploit this by injecting JavaScript payloads via the uselang=x-xss language override, which causes crafted message keys to be rendered unescaped.
This issue affects Mediawiki - ApprovedRevs extension: from 1.39.X before 1.39.13, from 1.42.X before 1.42.7, from 1.43.X before 1.43.2.
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Analysis
by VulDB Data Team • 07/07/2025
The vulnerability identified as CVE-2025-53487 represents a critical stored cross-site scripting weakness within the ApprovedRevs extension for MediaWiki platforms. This flaw exists in multiple version ranges including 1.39.X before 1.39.13, 1.42.X before 1.42.7, and 1.43.X before 1.43.2, making it a widespread concern for organizations relying on MediaWiki's revision approval functionality. The vulnerability stems from improper input sanitization mechanisms that fail to adequately escape system messages before rendering them as raw HTML content. This allows malicious actors to persistently inject malicious JavaScript code that executes whenever affected pages are loaded by unsuspecting users.
The technical exploitation of this vulnerability occurs through a specific attack vector involving the uselang=x-xss language override parameter. When attackers manipulate this parameter to inject crafted message keys, the system processes these keys without proper HTML escaping mechanisms. This creates an environment where JavaScript payloads can be stored within the system messages and subsequently executed in the context of users' browsers. The flaw operates at the intersection of user input handling and output rendering, where the extension fails to implement proper contextual escaping for different content types. This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and represents a classic case of insufficient output escaping in web applications.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to perform a wide range of malicious activities including session hijacking, data exfiltration, and privilege escalation within the MediaWiki environment. An attacker who successfully exploits this vulnerability could gain access to user sessions, potentially compromising administrative accounts and gaining unauthorized access to sensitive content management systems. The stored nature of this XSS vulnerability means that once exploited, the malicious payloads persist indefinitely until manually removed by system administrators, creating a long-term security risk. This vulnerability particularly affects collaborative environments where multiple users interact with revision approval systems, as it could be leveraged to compromise the integrity of content management workflows.
Organizations should immediately implement mitigations including applying the patched versions of the ApprovedRevs extension for MediaWiki as specified in the affected version ranges. The recommended approach involves upgrading to versions 1.39.13, 1.42.7, or 1.43.2 respectively, which contain the necessary fixes for the HTML escaping mechanisms. Additionally, administrators should consider implementing web application firewalls with XSS detection capabilities and conducting comprehensive security reviews of all MediaWiki extensions to identify similar vulnerabilities. Network-level protections such as content security policies can provide additional defense-in-depth measures, though these are secondary to proper code-level fixes. The vulnerability also highlights the importance of proper input validation and output escaping practices in web applications, particularly when handling user-provided content in system messages. Organizations should conduct thorough testing to ensure that all affected versions have been properly patched and that no legacy installations remain vulnerable to this or similar cross-site scripting attacks.