CVE-2023-53688 is a vulnerability identified in Nagios XI, a widely used IT infrastructure monitoring solution. The flaw exists in the Hypermap Replay component of Nagios XI versions prior to 5.11.3, where user-supplied input is not properly sanitized or escaped, leading to a Cross-Site Scripting (XSS) vulnerability (CWE-79). This allows an attacker to inject malicious JavaScript code that executes within the context of a victim’s browser session, potentially enabling theft of session cookies, credential theft, or unauthorized actions within the Nagios XI web interface. Additionally, the component lacks sufficient anti-Cross-Site Request Forgery (CSRF) protections (CWE-352) on state-changing operations, allowing attackers to trick authenticated users into performing unintended actions by submitting crafted requests. The vulnerability is remotely exploitable over the network without requiring authentication or privileges, but it does require user interaction (e.g., clicking a malicious link). The CVSS 4.0 base score is 5.1 (medium severity), reflecting the moderate impact on confidentiality and integrity with no impact on availability. No known exploits have been reported in the wild yet. The vulnerability highlights the importance of proper input validation and CSRF defenses in web applications, especially those managing critical infrastructure monitoring.

For European organizations, the exploitation of CVE-2023-53688 could lead to unauthorized disclosure of sensitive monitoring data, session hijacking, and manipulation of monitoring configurations or alerts. This could degrade the integrity and reliability of IT infrastructure monitoring, potentially delaying detection of outages or security incidents. Attackers could leverage XSS to pivot into further attacks within the network or escalate privileges if combined with other vulnerabilities. The CSRF weakness could allow attackers to alter monitoring settings or suppress alerts, impacting operational security. Organizations relying on Nagios XI for critical infrastructure monitoring, including energy, finance, telecommunications, and government sectors, face increased risk of operational disruption or data compromise. The medium severity rating suggests a moderate but non-trivial risk, especially if combined with social engineering to induce user interaction.

The primary mitigation is to upgrade Nagios XI to version 5.11.3 or later, where the vulnerability has been addressed. In the absence of immediate patching, organizations should implement strict input validation and output encoding on the Hypermap Replay component to prevent script injection. Enforcing robust anti-CSRF tokens on all state-changing requests is critical to mitigate CSRF attacks. Network-level protections such as web application firewalls (WAFs) can be configured to detect and block typical XSS payloads targeting Nagios XI. User awareness training to recognize phishing or malicious links can reduce the risk of user interaction exploitation. Additionally, monitoring web server logs for suspicious requests and anomalous user actions can help detect attempted exploitation. Segmentation of monitoring infrastructure and limiting access to Nagios XI interfaces to trusted networks or VPNs can further reduce exposure.