CVE-2025-60424 identifies a security vulnerability in the OTP (One-Time Password) verification mechanism of Nagios Fusion versions v2024R1.2 and v2024R2. The core issue is the absence of rate limiting controls on OTP verification attempts, which allows an attacker to perform brute force attacks against the OTP verification process. Normally, OTP systems are designed to prevent repeated guessing by limiting the number of attempts within a given timeframe. However, in this case, the lack of such controls means an attacker can systematically try multiple OTP codes until the correct one is found, effectively bypassing the multi-factor authentication layer. This bypass grants unauthorized access to the Nagios Fusion interface, which is a centralized monitoring tool used to oversee IT infrastructure and network health. Unauthorized access to Nagios Fusion can lead to exposure or manipulation of monitoring data, disruption of monitoring services, and potentially provide a foothold for further attacks within the network. Although no public exploits have been reported yet, the vulnerability is publicly disclosed and thus could be targeted by attackers. The vulnerability does not require user interaction beyond the brute force attempts and does not specify any prerequisite authentication, indicating it can be exploited remotely. The lack of a CVSS score necessitates an independent severity assessment based on the potential impact and exploitability.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of their IT monitoring infrastructure. Nagios Fusion is widely used in enterprise environments to monitor critical systems, networks, and applications. Unauthorized access through OTP bypass could allow attackers to disable alerts, manipulate monitoring data, or gain insights into network topology and vulnerabilities. This could facilitate further attacks such as lateral movement, data exfiltration, or disruption of services. Organizations in sectors such as finance, telecommunications, energy, and government are particularly vulnerable due to their reliance on continuous monitoring and the sensitivity of their data. The absence of rate limiting increases the likelihood of successful brute force attacks, especially if attackers have access to network connectivity to the Nagios Fusion server. The impact extends beyond individual organizations to potentially affect supply chains and critical infrastructure across Europe, increasing systemic risk.

To mitigate this vulnerability, organizations should immediately implement rate limiting controls on the OTP verification endpoint to restrict the number of attempts from a single source within a defined time window. This can be done via web application firewalls (WAFs), reverse proxies, or application-level controls if patching is not immediately available. Monitoring and alerting on abnormal authentication attempts should be enhanced to detect brute force activity early. Organizations should also review and tighten access controls around Nagios Fusion, including network segmentation to limit exposure of the management interface. Applying vendor patches or updates as soon as they are released is critical. In the interim, consider disabling OTP authentication if it cannot be secured or supplementing it with additional authentication factors. Conducting penetration testing and vulnerability assessments focused on authentication mechanisms can help identify residual risks. Finally, educating administrators about this vulnerability and encouraging prompt response to suspicious activity will improve overall security posture.