CVE-2025-62662 identifies a Stored Cross-Site Scripting (XSS) vulnerability in the AdvancedSearch Extension of Mediawiki, an open-source wiki platform widely used for collaborative documentation and knowledge management. The vulnerability arises from improper neutralization of input during web page generation, specifically in the AdvancedSearch Extension before version 1.39 on the master branch. Stored XSS means that malicious scripts injected by an attacker are saved on the server and executed in the browsers of users who access the affected pages. This can lead to theft of session cookies, user impersonation, defacement, or redirection to malicious sites. The vulnerability does not require authentication or user interaction, increasing its risk profile. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L) indicates network attack vector, low attack complexity, no privileges or user interaction needed, and limited impact on confidentiality, integrity, and availability. No known exploits have been reported in the wild, and no official patches have been linked yet. The flaw stems from insufficient input validation and output encoding in the extension's code that processes search queries or results. This vulnerability is classified under CWE-79, a common and critical web security weakness. Organizations running Mediawiki with the AdvancedSearch Extension should consider this a significant risk, especially if the wiki is accessible externally or contains sensitive information. Attackers could leverage this vulnerability to execute arbitrary JavaScript in users' browsers, potentially compromising user accounts or internal data.

For European organizations, the impact of CVE-2025-62662 can be substantial depending on the deployment context of Mediawiki. Public-facing wikis used for documentation, knowledge sharing, or collaboration could be exploited to inject malicious scripts that compromise user sessions or redirect users to phishing or malware sites. Internal wikis containing sensitive corporate or governmental information could be targeted to escalate attacks or exfiltrate data. The vulnerability's ability to execute scripts without authentication or user interaction increases the risk of automated exploitation and widespread impact. This could lead to reputational damage, data breaches, and disruption of knowledge management workflows. Given the widespread use of Mediawiki in public sector, academia, and enterprises across Europe, the threat could affect critical infrastructure and organizations with high compliance requirements such as GDPR. The limited scope of impact on confidentiality, integrity, and availability reduces the risk of full system compromise but does not eliminate the risk of targeted attacks against users or data integrity.

1. Monitor official Wikimedia Foundation channels for patches or updates to the AdvancedSearch Extension and apply them promptly once available. 2. In the interim, disable or restrict access to the AdvancedSearch Extension if feasible, especially on public-facing wikis. 3. Implement strict input validation and output encoding on all user-supplied data related to search queries and results within the Mediawiki environment. 4. Deploy Web Application Firewalls (WAFs) with rules to detect and block common XSS payloads targeting Mediawiki. 5. Conduct security audits and code reviews of custom or third-party Mediawiki extensions to identify similar input sanitization issues. 6. Educate users and administrators about the risks of XSS and encourage cautious behavior regarding links and scripts in wiki content. 7. Use Content Security Policy (CSP) headers to restrict execution of unauthorized scripts in browsers accessing the wiki. 8. Regularly monitor logs and user reports for suspicious activity indicative of exploitation attempts. 9. Consider isolating the wiki environment or restricting access to trusted networks to reduce exposure. 10. Maintain up-to-date backups of wiki content to enable recovery in case of defacement or data tampering.