CVE-2026-89054

OpenNMS missing authorization on /api/v2 PATCH endpoints allows unauthenticated configuration changes

Published Sep 10, 2026 CVSS 3.1 · 8.2 High EPSS < 1% KEV · Not listed
Description
A missing authorization vulnerability in OpenNMS Horizon allows configuration changes without authentication. The Spring Security policy for the /api/v2 REST API defines authorization rules for every HTTP method except PATCH, so the shipped @PATCH configuration endpoints for event configuration and SNMP data collection (which enable and disable event definitions and data-collection sources) are reachable with no authorization enforced. An unauthenticated attacker able to reach the web UI can disable event definitions and SNMP data collection, suppressing event and alarm generation and stopping metric collection - silently degrading monitoring and detection - with the change persisted and reloaded into the running system.



The solution is to upgrade to Horizon 36.0.4 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.

Remediation

Vendor Solution

Upgrade to Horizon 36.0.4 or newer.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared The Opennms Group
The Opennms Group horizon
Vendors & Products The Opennms Group
The Opennms Group horizon
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A missing authorization vulnerability in OpenNMS Horizon allows configuration changes without authentication. The Spring Security policy for the /api/v2 REST API defines authorization rules for every HTTP method except PATCH, so the shipped @PATCH configuration endpoints for event configuration and SNMP data collection (which enable and disable event definitions and data-collection sources) are reachable with no authorization enforced. An unauthenticated attacker able to reach the web UI can disable event definitions and SNMP data collection, suppressing event and alarm generation and stopping metric collection - silently degrading monitoring and detection - with the change persisted and reloaded into the running system. The solution is to upgrade to Horizon 36.0.4 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.
Title OpenNMS missing authorization on /api/v2 PATCH endpoints allows unauthenticated configuration changes
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
OpenNMS
Published
Updated
Sep 10, 2026, 8:03 PM
Reserved
Sep 10, 2026, 5:29 PM
Status
Awaiting Analysis
Published
Sep 10, 2026, 8:17 PM
Modified
Sep 18, 2026, 7:21 PM