CVE-2026-19182 OpenNMS v2 Alarm REST API inverted authorization check lets ROLE_REST users acknowledge alarms as any user and bypass read-only

An incorrect authorization check in the v2 Alarm REST API in OpenNMS Meridian and Horizon allows a low-privileged authenticated user ROLEREST to acknowledge, escalate, or clear alarms recorded as an arbitrary username, and, when also assigned ROLEREADONLY, to modify alarm state despite the...