CVE-2025-53484 is a cross-site scripting (XSS) vulnerability classified under CWE-79, affecting the SecurePoll extension of the Wikimedia Foundation's Mediawiki software. The vulnerability arises due to improper neutralization of user-controlled inputs during web page generation. Specifically, the issue is present in the handling of poll option inputs in VotePage.php and user-controllable page names in the ResultPage::getPagesTab() and getErrorsTab() functions. Because these inputs are not properly escaped or sanitized, an attacker can inject malicious JavaScript code into the web pages generated by the SecurePoll extension. This injected script can execute in the browsers of users who view the affected pages, potentially allowing attackers to hijack user sessions, steal cookies, perform actions on behalf of the user, or conduct other malicious activities within the context of the vulnerable Mediawiki instance. The vulnerability affects multiple versions of the SecurePoll extension: from 1.39.x before 1.39.13, from 1.42.x before 1.42.7, and from 1.43.x before 1.43.2. No public exploits are currently known, and no CVSS score has been assigned yet. The vulnerability was published on July 4, 2025, and is considered a significant security risk given the widespread use of Mediawiki in collaborative environments and knowledge bases.

For European organizations, the impact of this XSS vulnerability can be substantial, especially for those relying on Mediawiki with the SecurePoll extension for internal or public-facing knowledge management, collaboration, or polling. Successful exploitation could lead to session hijacking, allowing attackers to impersonate legitimate users, potentially gaining unauthorized access to sensitive information or administrative functions. This could result in data leakage, unauthorized content modification, or disruption of collaborative processes. Additionally, if the Mediawiki instance is used for public engagement or decision-making (e.g., polls), the integrity of the polling process could be compromised, undermining trust. The vulnerability could also serve as a foothold for further attacks within an organization's network if exploited by a sophisticated adversary. Given the collaborative nature of Mediawiki, the risk extends to both confidentiality and integrity of information. The absence of known exploits currently reduces immediate risk, but the public disclosure increases the likelihood of future exploitation attempts.

European organizations should promptly update the SecurePoll 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. If immediate patching is not feasible, organizations should implement strict input validation and output encoding for poll options and page names to neutralize potentially malicious scripts. Employing Content Security Policy (CSP) headers can help mitigate the impact of injected scripts by restricting the sources from which scripts can be loaded and executed. Additionally, organizations should review and restrict user permissions to limit who can create or modify polls and page names, reducing the attack surface. Monitoring web server logs and Mediawiki activity for unusual input patterns or errors related to poll pages can help detect attempted exploitation. Finally, educating users about the risks of XSS and encouraging cautious behavior when interacting with polls or user-generated content can reduce the likelihood of successful attacks.