CVE-2023-7313 is a cross-site scripting (XSS) vulnerability identified in Nagios XI, a widely used IT infrastructure monitoring solution. The flaw exists in versions prior to 5.11.3 within the Bulk Modifications tool, where user-supplied input is insufficiently validated or escaped before being incorporated into web pages. This improper neutralization of input (CWE-79) enables attackers to inject arbitrary JavaScript code that executes in the context of a victim's browser session. The vulnerability's CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), and user interaction required (UI:P). The partial privileges required suggest that an attacker must have some limited access to the system, but no authentication is needed to trigger the vulnerability. The impact primarily affects confidentiality and integrity by enabling session hijacking, theft of sensitive information, or execution of unauthorized commands within the Nagios XI web interface. Although no known exploits are currently reported in the wild, the vulnerability poses a tangible risk due to the common use of Nagios XI in monitoring critical infrastructure and enterprise environments. The vulnerability is classified as medium severity with a CVSS score of 5.1, reflecting moderate risk. The lack of a patch link in the provided data suggests that users should verify the availability of updates from Nagios and apply version 5.11.3 or later, which addresses this issue. Organizations should also review their input validation and output encoding practices to prevent similar injection flaws.

For European organizations, the impact of CVE-2023-7313 can be significant, particularly for those relying on Nagios XI for monitoring critical IT infrastructure, telecommunications, energy grids, and financial systems. Successful exploitation could allow attackers to execute malicious scripts within the browsers of administrators or users interacting with the Bulk Modifications tool, potentially leading to session hijacking, credential theft, or unauthorized configuration changes. This could disrupt monitoring capabilities, delay incident response, and expose sensitive operational data. Given the interconnected nature of European IT environments and regulatory requirements such as GDPR, a breach stemming from this vulnerability could result in compliance violations and reputational damage. The medium severity rating indicates a moderate risk, but the potential for lateral movement or escalation within networks elevates the threat in sensitive sectors. Organizations with limited patch management processes or those using older Nagios XI versions are particularly vulnerable.

1. Immediately upgrade Nagios XI installations to version 5.11.3 or later, where this vulnerability is resolved. 2. Implement strict input validation and output encoding in all web application components, especially those handling user-supplied data like the Bulk Modifications tool. 3. Restrict access to the Nagios XI interface to trusted networks and users using network segmentation and access control lists (ACLs). 4. Employ web application firewalls (WAFs) with rules targeting XSS attack patterns to provide an additional layer of defense. 5. Conduct regular security audits and penetration testing focused on web interface vulnerabilities. 6. Educate administrators and users about the risks of XSS and the importance of cautious interaction with web interfaces. 7. Monitor logs and network traffic for unusual activity that could indicate exploitation attempts. 8. Apply the principle of least privilege to Nagios XI user accounts to limit the impact of compromised credentials. 9. Keep all related software and dependencies up to date to reduce the attack surface.