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CVE-2026-89054

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

CVSS 3.1 8.2 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-89054

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-89054

Published

Horizon

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "The OpenNMS Group",
                    "product": "Horizon",
                    "repo": "https://github.com/OpenNMS",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "36.0.0",
                            "lessThan": "36.0.4",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

Original source record · Cite this exact observation · Complete original publisher JSON