CVE-2023-7318 is a cross-site scripting (XSS) vulnerability classified under CWE-79, found in Nagios XI versions prior to 2024R1.0.2. The vulnerability exists due to insufficient validation or escaping of user-supplied input on the Nagios Core Command Expansion page. This flaw allows an attacker to inject malicious scripts that execute in the context of a victim's browser when they visit a crafted URL or interact with malicious content. The CVSS 4.0 vector indicates the attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:L, indicating low privileges), and requires user interaction (UI:P). The vulnerability affects confidentiality and integrity by enabling script execution that could steal session tokens, manipulate displayed data, or perform unauthorized actions on behalf of the user. While no known exploits are currently reported in the wild, the vulnerability's presence in a widely used IT infrastructure monitoring tool makes it a potential target for attackers seeking to compromise monitoring environments. The Nagios Core Command Expansion page is a critical interface for command execution, making this vulnerability particularly sensitive. The vulnerability is mitigated by upgrading to Nagios XI version 2024R1.0.2 or later, which includes proper input sanitization and output encoding to neutralize malicious input. Organizations should also review their web application firewall (WAF) rules and monitor for suspicious activity related to this endpoint.

For European organizations, the impact of CVE-2023-7318 can be significant, especially for those relying on Nagios XI for monitoring critical IT infrastructure. Successful exploitation could lead to session hijacking, unauthorized command execution, and data theft within the monitoring platform, potentially disrupting incident detection and response capabilities. This could cascade into broader operational impacts, including delayed detection of outages or security incidents. Organizations in sectors such as energy, finance, telecommunications, and government are particularly at risk due to their reliance on continuous monitoring and the sensitivity of their data. The vulnerability's exploitation could also facilitate lateral movement within networks if attackers gain control over monitoring systems. Although the vulnerability requires user interaction, phishing or social engineering campaigns could be used to trick administrators or operators into triggering the exploit. The medium severity rating reflects a moderate risk, but the critical role of Nagios XI in infrastructure monitoring elevates the potential operational impact.

1. Immediately upgrade Nagios XI to version 2024R1.0.2 or later, which contains the patch for this vulnerability. 2. Implement strict input validation and output encoding on the Nagios Core Command Expansion page to prevent injection of malicious scripts. 3. Deploy or update web application firewall (WAF) rules to detect and block suspicious payloads targeting the vulnerable endpoint. 4. Conduct user awareness training focused on phishing and social engineering to reduce the risk of user interaction with malicious links. 5. Monitor web server and application logs for unusual requests or error patterns related to the Command Expansion page. 6. Restrict access to the Nagios XI web interface to trusted IP ranges and enforce multi-factor authentication (MFA) for all users. 7. Regularly review and audit Nagios XI configurations and permissions to minimize exposure. 8. Consider network segmentation to isolate monitoring infrastructure from general user networks to limit attack surface.