CVE-2025-44824 is an authorization vulnerability classified under CWE-863 (Incorrect Authorization) affecting Nagios Log Server versions prior to 2024R1.3.2. The flaw allows any authenticated user with read-only API access to invoke the /nagioslogserver/index.php/api/system/stop?subsystem=elasticsearch endpoint, which stops the Elasticsearch service despite the API response indicating failure with the message "Could not stop elasticsearch." This discrepancy suggests that the API does not properly enforce authorization checks or does not accurately report the outcome of the stop command. Elasticsearch is a core component of Nagios Log Server responsible for indexing and searching log data; stopping it causes a denial of service by disrupting log ingestion and query capabilities. The vulnerability requires authentication but no elevated privileges beyond read-only API access, and no user interaction beyond API call execution. The CVSS 3.1 base score is 8.5 (high), reflecting network attack vector, low attack complexity, privileges required, no user interaction, scope change, no confidentiality impact, low integrity impact, and high availability impact. There are no known public exploits or patches at the time of publication, indicating a window of exposure for affected users. This vulnerability highlights a critical authorization bypass that could be leveraged by insider threats or compromised accounts to disrupt monitoring infrastructure.

For European organizations, the impact of this vulnerability is significant due to the reliance on Nagios Log Server for centralized log management, security monitoring, and compliance reporting. Disruption of the Elasticsearch service can halt log indexing and search functions, impairing incident detection, forensic investigations, and operational visibility. This can delay response to security incidents and increase risk exposure. Critical sectors such as finance, energy, healthcare, and government agencies in Europe that use Nagios Log Server for monitoring may experience operational downtime or degraded security posture. The denial of service could also affect regulatory compliance where continuous monitoring and log retention are mandated. Additionally, the ease of exploitation by any authenticated user with read-only API access increases the threat surface, especially in environments with weak access controls or shared credentials.

Immediate mitigation steps include restricting API access to trusted and minimal users, enforcing strong authentication and authorization policies, and monitoring API usage for suspicious stop commands targeting Elasticsearch. Network segmentation and firewall rules should limit access to the Nagios Log Server API endpoints. Organizations should prepare to apply vendor patches or updates as soon as they become available for version 2024R1.3.2 or later. In the interim, consider disabling or restricting the vulnerable API endpoint if feasible. Implementing robust logging and alerting on service stop events can help detect exploitation attempts early. Regularly audit user privileges to ensure that read-only API access is granted only to necessary personnel. Finally, organizations should review incident response plans to address potential monitoring outages caused by this vulnerability.