CVE-2025-53497 is a security vulnerability classified under CWE-79, which pertains to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This specific vulnerability affects the RelatedArticles extension of the Mediawiki software developed by the Wikimedia Foundation. Mediawiki is a widely used open-source wiki platform, powering many collaborative websites including Wikipedia. The vulnerability exists in versions 1.43.x of the RelatedArticles extension prior to 1.43.2. It allows an attacker to inject malicious scripts that are stored and later executed in the context of users viewing affected pages. Stored XSS is particularly dangerous because the malicious payload is saved on the server and delivered to any user accessing the compromised content, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The vulnerability arises due to insufficient sanitization or encoding of user-supplied input when generating web pages, allowing script code to be embedded and executed in victim browsers. No CVSS score has been assigned yet, and no known exploits have been reported in the wild as of the publication date (July 7, 2025). However, given the nature of stored XSS and the popularity of Mediawiki, this vulnerability represents a significant risk if left unpatched. The absence of a patch link suggests that a fix may be forthcoming or pending release. Organizations using Mediawiki with the RelatedArticles extension version 1.43.x before 1.43.2 should prioritize updating to the fixed version once available or apply interim mitigations to prevent exploitation.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on Mediawiki for internal knowledge bases, documentation, or public-facing collaborative platforms. Exploitation of stored XSS can lead to unauthorized access to sensitive information, session hijacking, and the spread of malware through trusted websites. This can compromise confidentiality and integrity of organizational data and disrupt availability if attackers leverage the vulnerability to perform further attacks such as defacement or phishing. Public institutions, educational entities, and enterprises that use Mediawiki extensively may face reputational damage and regulatory consequences under GDPR if personal data is exposed or manipulated. The collaborative nature of wikis means that many users with varying privilege levels access the platform, increasing the risk that malicious scripts could affect a broad user base. Additionally, attackers could use the vulnerability as a foothold to escalate privileges or pivot to other internal systems. The lack of known exploits currently reduces immediate risk but does not diminish the potential severity once exploit code becomes available.

1. Immediate upgrade to Mediawiki RelatedArticles extension version 1.43.2 or later once the patch is released. Monitor official Wikimedia Foundation channels for patch announcements. 2. Until a patch is available, implement strict input validation and output encoding on all user-generated content related to the RelatedArticles extension to neutralize potentially malicious scripts. 3. Employ Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of XSS attacks. 4. Conduct regular security audits and code reviews focusing on input handling in Mediawiki extensions. 5. Educate users about the risks of clicking suspicious links or executing unexpected scripts within the wiki environment. 6. Monitor logs and user activity for unusual behavior that could indicate exploitation attempts. 7. Consider isolating or restricting access to the RelatedArticles extension if it is not critical to operations until the vulnerability is resolved. 8. Use web application firewalls (WAF) with rules designed to detect and block XSS payloads targeting Mediawiki platforms.