Chamilo LMS, an open-source learning management system widely used in educational institutions, has a reflected cross-site scripting (XSS) vulnerability identified as CVE-2025-52476. This vulnerability exists in versions prior to 1.11.30 and is caused by improper neutralization of user-supplied input in the 'keyword_active' parameter within the admin/user_list.php script. Specifically, the application fails to adequately sanitize this parameter before reflecting it in the web page output, allowing an attacker to inject malicious JavaScript code. When a victim user, typically an administrator or someone with access to the admin interface, clicks on a crafted URL containing the malicious payload, the script executes in their browser context. This can lead to theft of session cookies, execution of unauthorized actions, or redirection to malicious sites. The vulnerability requires no authentication to exploit but does require user interaction (clicking a link). The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, user interaction needed, and low impact on integrity with no impact on confidentiality or availability. The vulnerability was publicly disclosed and patched in Chamilo LMS version 1.11.30. No known exploits have been reported in the wild to date. The CWE classification is CWE-79, which covers improper neutralization of input during web page generation, a common cause of XSS issues.

The primary impact of this vulnerability is the potential for attackers to execute arbitrary JavaScript in the context of the affected Chamilo LMS web application. This can lead to session hijacking, allowing attackers to impersonate legitimate users, including administrators, thereby gaining unauthorized access to sensitive educational data and user accounts. Additionally, attackers could perform actions on behalf of the victim, such as modifying user information or injecting malicious content. The reflected XSS nature means the attack is typically delivered via social engineering, requiring victims to click malicious links. While the vulnerability does not directly compromise system availability or confidentiality at a large scale, the compromise of administrative accounts could lead to broader security breaches, data leakage, and erosion of trust in the LMS platform. Educational institutions relying on Chamilo LMS for remote learning and student management could face operational disruptions and reputational damage if exploited.

To mitigate CVE-2025-52476, organizations should immediately upgrade Chamilo LMS to version 1.11.30 or later, where the vulnerability is patched. If immediate upgrade is not feasible, implement strict input validation and output encoding on the 'keyword_active' parameter to neutralize malicious scripts. Deploy a web application firewall (WAF) with rules to detect and block reflected XSS attack patterns targeting Chamilo LMS endpoints. Educate users, especially administrators, about the risks of clicking unsolicited or suspicious links, emphasizing phishing awareness. Regularly audit and monitor LMS logs for unusual access patterns or suspicious URL parameters. Additionally, consider implementing Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts within the LMS web pages. Finally, maintain a robust patch management process to ensure timely application of security updates.