CVE-2025-59115 is a stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79 that affects Windu CMS version 4.1. The vulnerability arises due to improper neutralization of input during web page generation on the logon page, where user-supplied data is not properly sanitized or validated. This allows an attacker to inject arbitrary HTML or JavaScript code that is stored persistently and executed when an administrator accesses the logs page. Because the malicious script runs in the context of the administrator's browser, it can lead to session hijacking, credential theft, or unauthorized administrative actions. The vulnerability is remotely exploitable without authentication and requires user interaction (the admin must visit the logs page). The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, user interaction required, and limited scope impact. The vulnerability was confirmed in version 4.1 and fixed in build 2250 of the same version. No public exploits have been reported yet, but the risk remains significant due to the potential impact on administrative control and data confidentiality. Windu CMS is a content management system used by various organizations, and this vulnerability could be leveraged to compromise websites and backend administrative functions.

For European organizations using Windu CMS version 4.1 or earlier, this vulnerability poses a risk of administrative account compromise and unauthorized control over website content and logs. Exploitation could lead to theft of sensitive information, defacement, or further pivoting into internal networks. The impact on confidentiality is moderate due to potential exposure of administrative sessions and data. Integrity can be compromised if attackers modify logs or website content. Availability impact is limited but could occur if attackers disrupt administrative functions. Since exploitation requires an administrator to visit the logs page, the risk depends on administrator behavior and access patterns. Organizations in sectors with high reliance on web presence and CMS platforms, such as government, media, and e-commerce in Europe, could face reputational damage and operational disruption. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially given the public disclosure and availability of the fix.

European organizations should immediately verify their Windu CMS version and upgrade to version 4.1 build 2250 or later where the vulnerability is patched. If immediate upgrade is not feasible, implement input validation and output encoding on the logon and logs pages to neutralize potentially malicious input. Restrict access to the logs page to trusted administrators only and consider additional monitoring for unusual activity or script injections. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in the administrator interface. Conduct regular security audits and penetration testing focused on CMS components. Educate administrators about the risks of clicking on untrusted links or inputs within the CMS environment. Finally, maintain up-to-date backups and incident response plans to quickly recover from any potential compromise.