CVE-2025-44824: Nagios Log Server Auth Bypass Vulnerability

CVE-2025-44824 Overview

CVE-2025-44824 is an authorization flaw in Nagios Log Server versions prior to 2024R1.3.2. Authenticated users holding only read-only API access can stop the Elasticsearch backend service by issuing a crafted request to the system control endpoint. The API returns an error message stating "Could not stop elasticsearch", yet the service is terminated regardless. The issue is tracked by the vendor as GL:NLS#474 and maps to CWE-863: Incorrect Authorization.

Critical Impact
A low-privileged authenticated user can disable the Elasticsearch service that underpins Nagios Log Server, halting log ingestion, search, and alerting until an administrator restores the subsystem.

Affected Products

Nagios Log Server 2024 R1
Nagios Log Server 2024 R1.0.1, R1.0.2, R1.1, R1.2, R1.3
Nagios Log Server 2024 R1.3.1 (all releases prior to 2024R1.3.2)

Discovery Timeline

2025-10-07 - CVE-2025-44824 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-44824

Vulnerability Analysis

The flaw resides in the Nagios Log Server system control API exposed at /nagioslogserver/index.php/api/system/stop. The endpoint accepts a subsystem query parameter that selects which backend service to stop. When subsystem=elasticsearch is supplied, the handler proceeds to stop the Elasticsearch process without validating that the caller holds administrative privileges.

Any authenticated account, including accounts limited to read-only API access, can invoke the endpoint. The API response contains the string "Could not stop elasticsearch", which misleads defenders reviewing logs into believing the request failed. In practice the underlying service is terminated, which suppresses further log ingestion and correlation.

Because Elasticsearch stores the log data that Nagios Log Server indexes and queries, stopping the service produces an availability outage across dashboards, saved searches, and alerts driven by log content.

Root Cause

The root cause is missing role-based authorization on the system/stop action. The handler enforces authentication but does not check that the requester has the administrator role required to manage backend subsystems. This is a classic CWE-863 incorrect authorization pattern where an access decision considers identity but not privilege level.

Attack Vector

Exploitation requires network reachability to the Nagios Log Server web interface and valid credentials for any account with API access. An attacker sends an authenticated HTTP GET or POST request to /nagioslogserver/index.php/api/system/stop?subsystem=elasticsearch using the account's API key. The server terminates the Elasticsearch service and returns a misleading failure message. The attack can be repeated whenever an administrator restarts the service, creating a sustained denial-of-service condition. A public proof-of-concept is available at the GitHub DoS PoC repository.

Detection Methods for CVE-2025-44824

Indicators of Compromise

HTTP requests to /nagioslogserver/index.php/api/system/stop with the parameter subsystem=elasticsearch originating from non-administrative user sessions or API keys.
API responses containing the string "Could not stop elasticsearch" correlated with an Elasticsearch process exit event on the host.
Unexpected termination of the elasticsearch service or gaps in log ingestion timelines within Nagios Log Server dashboards.

Detection Strategies

Enable web server access logging on the Nagios Log Server front end and alert on any call to the api/system/stop path.
Monitor Elasticsearch service state and generate an alert whenever the process transitions to stopped outside of a scheduled maintenance window.
Cross-reference API audit logs against the user role directory to flag privileged actions performed by read-only accounts.

Monitoring Recommendations

Forward Nagios Log Server web access logs and Elasticsearch service events to a central SIEM for correlation and long-term retention.
Track API key usage by endpoint and alert on read-only tokens invoking administrative actions.
Baseline normal Elasticsearch uptime and generate alerts when the service stops unexpectedly or repeatedly within a short window.

How to Mitigate CVE-2025-44824

Immediate Actions Required

Upgrade Nagios Log Server to version 2024R1.3.2 or later, which contains the vendor fix for GL:NLS#474.
Audit all Nagios Log Server user accounts and API keys, disabling any that are unused or unnecessarily provisioned.
Restrict network access to the Nagios Log Server web interface to trusted management networks only.

Patch Information

Nagios addressed the vulnerability in Nagios Log Server 2024R1.3.2. Release details are available in the Nagios Log Server Changelog. Apply the update through the standard Nagios upgrade procedure and verify the running version after installation.

Workarounds

Place the Nagios Log Server administrative interface behind a reverse proxy or VPN that limits access to administrator workstations.
Rotate API keys for any account that does not require API access and revoke tokens from users who only need the web UI.
Monitor and alert on invocations of /api/system/stop and automatically restart Elasticsearch on unexpected shutdown until the patch is deployed.

bash

# Example web server rule to block the vulnerable endpoint at the edge
# (Apply until Nagios Log Server 2024R1.3.2 is installed)
location ~* /nagioslogserver/index\.php/api/system/stop {
    deny all;
    return 403;
}