CVE-2026-19182
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
An incorrect authorization check in the v2 Alarm REST API in OpenNMS Meridian and Horizon allows a low-privileged authenticated user (ROLE_REST) to acknowledge, escalate, or clear alarms recorded as an arbitrary username, and, when also assigned ROLE_READONLY, to modify alarm state despite the read-only restriction. A credential check is guarded by an inverted condition, so it never executes for a real (non-blank) username.
Risk Assessment
An attacker can compromise the integrity of alarm state and audit records, potentially leading to unauthorized changes in monitoring and hiding incidents.
Recommendation
Upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 or newer. Also ensure systems are not directly accessible from the Internet.
Original NVD description (English source)
An incorrect authorization check in the v2 Alarm REST API in OpenNMS Meridian and Horizon allows a low-privileged authenticated user (ROLE_REST) to acknowledge, escalate, or clear alarms recorded as an arbitrary username, and, when also assigned ROLE_READONLY, to modify alarm state despite the read-only restriction. A credential check that should restrict these operations is guarded by an inverted condition, so it never executes for a real (non-blank) username. This can potentially allow an attacker to compromise the integrity of alarm state and audit records. The solution is to upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 or newer. Meridian and Horizon installation instructions state that they are intended for installation within an organization's private networks and should not be directly accessible from the Internet.