CVE-2025-11937 identifies a stored Cross-site Scripting (XSS) vulnerability in the SecurePoll extension of Mediawiki, a widely used open-source wiki platform maintained by the Wikimedia Foundation. The vulnerability stems from improper neutralization of user-supplied input during web page generation, classified under CWE-79. Specifically, the SecurePoll extension fails to adequately sanitize or encode input data before rendering it in web pages, enabling attackers to inject malicious JavaScript code that is stored persistently. When other users access the affected pages, the malicious script executes in their browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed with the victim's privileges. The vulnerability affects the master branch of the SecurePoll extension, indicating it is present in the latest development version at the time of disclosure. 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 required, and low to limited impacts on confidentiality, integrity, and availability. Although no known exploits are reported in the wild, the nature of stored XSS makes it a significant risk if weaponized. Mediawiki is extensively used by organizations for collaborative knowledge management, including many European public sector entities, making this vulnerability relevant for those environments. The lack of an official patch link suggests that remediation is pending or in progress. Technical mitigation involves proper input validation, output encoding, and adopting Content Security Policy (CSP) headers to reduce script execution risk. Monitoring and incident response readiness are also important to detect potential exploitation attempts.

For European organizations, the impact of CVE-2025-11937 can be substantial, particularly for those relying on Mediawiki with the SecurePoll extension for internal or public-facing knowledge bases and polling functionalities. Exploitation could allow attackers to execute arbitrary scripts in the context of legitimate users, leading to theft of sensitive information such as authentication tokens, user credentials, or internal data. This can facilitate further attacks like privilege escalation or lateral movement within networks. The vulnerability could also be leveraged to manipulate poll results or disrupt collaborative decision-making processes, undermining trust and operational integrity. Public sector organizations, educational institutions, and NGOs that use Mediawiki extensively may face reputational damage and compliance risks under GDPR if personal data is compromised. Although the CVSS score is medium, the ease of exploitation without authentication or user interaction increases the threat level. The absence of known exploits currently provides a window for proactive mitigation, but the stored nature of the XSS means that once exploited, the impact can persist until the malicious content is removed.

1. Apply official patches or updates from the Wikimedia Foundation as soon as they become available for the SecurePoll extension. 2. Until patches are released, disable or restrict access to the SecurePoll extension if feasible, especially on public-facing instances. 3. Implement strict input validation on all user-supplied data fields related to polling features, ensuring that potentially dangerous characters are sanitized or escaped. 4. Employ robust output encoding techniques (e.g., HTML entity encoding) when rendering user input in web pages to prevent script execution. 5. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 6. Conduct regular security audits and code reviews focusing on input handling in Mediawiki extensions. 7. Monitor web server logs and application behavior for unusual activities indicative of XSS exploitation attempts. 8. Educate administrators and users about the risks of XSS and encourage prompt reporting of suspicious content. 9. Consider web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting Mediawiki. 10. Backup Mediawiki content regularly to enable quick restoration if malicious scripts are injected.