CVE-2025-58122 is a vulnerability identified in Checkmk, a widely used IT infrastructure monitoring software developed by Checkmk GmbH. The issue stems from improper handling of insufficient permissions (CWE-280) in version 2.4.0 before patch 2.4.0p16. Specifically, the REST API does not adequately validate the permissions of low-privileged users attempting to modify notification parameters. Notification parameters typically control alerting mechanisms, such as who receives alerts and under what conditions. By exploiting this flaw, an attacker with low-level access can alter these parameters, potentially redirecting alerts, suppressing notifications, or gaining insight into system states that should be restricted. The vulnerability is exploitable remotely over the network without requiring user interaction or elevated privileges beyond low-level access, making it relatively easy to exploit in environments where low-privileged accounts exist. The CVSS 4.0 base score is 5.3 (medium severity), reflecting moderate impact on confidentiality, integrity, and availability. No known public exploits have been reported, but the risk remains significant due to the potential for unauthorized actions and information disclosure within monitored environments. The lack of patch links suggests that organizations should monitor Checkmk's official channels for updates or consider interim mitigations such as restricting API access. This vulnerability highlights the importance of strict permission checks in REST APIs, especially in security-critical monitoring tools.

For European organizations, the impact of CVE-2025-58122 can be significant, particularly for those relying on Checkmk to monitor critical IT infrastructure, industrial control systems, or sensitive data centers. Unauthorized modification of notification parameters can lead to missed alerts for critical incidents, delayed responses to outages or security events, and potential exposure of sensitive monitoring data. This can degrade operational reliability and increase the risk of undetected security breaches. Organizations in sectors such as finance, healthcare, energy, and government are especially vulnerable due to their reliance on timely and accurate monitoring. Furthermore, attackers could manipulate alerts to mask ongoing attacks or cause confusion in incident response teams. Although the vulnerability requires low-privileged access, many environments have multiple users with such access, increasing the attack surface. The absence of user interaction and network-based exploitability further raise the threat level. Overall, the vulnerability could undermine trust in monitoring systems and complicate compliance with European data protection and cybersecurity regulations.

1. Immediately upgrade Checkmk installations from version 2.4.0 to version 2.4.0p16 or later once patches are released by Checkmk GmbH. 2. Until patches are available, restrict REST API access strictly to trusted users and IP addresses using network segmentation, firewall rules, or API gateway controls. 3. Review and audit all low-privileged user accounts to ensure minimal necessary permissions and remove any unnecessary accounts. 4. Implement monitoring and alerting on changes to notification parameters to detect unauthorized modifications quickly. 5. Enforce strong authentication and authorization mechanisms for API access, including multi-factor authentication where possible. 6. Conduct regular security assessments and penetration tests focusing on API endpoints and permission enforcement. 7. Educate administrators and users about the risks of improper permission handling and encourage prompt reporting of suspicious activities. 8. Maintain an inventory of all Checkmk instances and ensure they are included in vulnerability management programs. 9. Consider deploying Web Application Firewalls (WAFs) or API security tools that can detect and block anomalous API requests targeting notification parameters. 10. Stay informed through Checkmk security advisories and subscribe to vulnerability notification services.