CVE-2024-13992 is a cross-site scripting (XSS) vulnerability classified under CWE-79 affecting Nagios XI versions prior to 2024R1.1. The vulnerability exists in the page-missing.php script, which handles 404 error pages. This component fails to properly validate or escape user-supplied input embedded in the URL, allowing attackers to inject malicious JavaScript code. When a victim visits a crafted URL leading to the missing page, the injected script executes in the context of the Nagios XI web application domain. This can enable attackers to steal session cookies, perform actions on behalf of the user, or conduct phishing attacks within the trusted domain. The vulnerability requires no authentication but does require the victim to interact by clicking a malicious link, typically delivered via email or another website. The CVSS 4.0 base score is 5.1, reflecting medium severity due to network attack vector, low attack complexity, no privileges required, but user interaction needed. There are no known exploits in the wild, and no patches were linked in the provided data, indicating the need for vendor updates. The vulnerability primarily threatens confidentiality and integrity of user sessions and data within Nagios XI but does not affect system availability. Nagios XI is widely used for IT infrastructure monitoring, making this vulnerability relevant for organizations relying on it for critical system oversight.

For European organizations, exploitation of CVE-2024-13992 could lead to unauthorized access to monitoring dashboards, session hijacking, and potential manipulation of monitoring data or alerts. This could undermine trust in monitoring results, delay incident response, or facilitate further attacks by masking system issues. Organizations in sectors such as finance, energy, telecommunications, and government, which rely heavily on Nagios XI for infrastructure monitoring, may face increased risk. The compromise of monitoring systems can have cascading effects on operational security and compliance with regulations like GDPR if personal or sensitive data is exposed. While the vulnerability does not directly impact system availability, the integrity and confidentiality risks could disrupt security operations and incident management workflows. The requirement for user interaction limits mass exploitation but targeted phishing campaigns could be effective against key personnel. The absence of known exploits suggests a window for proactive mitigation before widespread abuse occurs.

European organizations should immediately verify their Nagios XI version and upgrade to 2024R1.1 or later once available to apply the official patch. In the interim, implement strict input validation and output encoding on the web server or reverse proxy to sanitize URL parameters, especially those leading to error pages. Deploy Content Security Policy (CSP) headers to restrict execution of inline scripts and untrusted sources, reducing XSS impact. Educate users and administrators about the risks of clicking unsolicited links, particularly those purporting to lead to Nagios XI resources. Monitor web server logs for suspicious requests to the page-missing.php endpoint containing unusual or encoded script content. Consider isolating Nagios XI interfaces behind VPNs or access controls to limit exposure to external attackers. Regularly review and update web application firewall (WAF) rules to detect and block XSS payloads targeting this vulnerability. Finally, maintain an incident response plan that includes monitoring for potential exploitation attempts and rapid patch deployment.