--- title: "CVE-2026-89054: OpenNMS Horizon - Broken Access Control" description: "OpenNMS Horizon contains a missing authorization vulnerability caused by lack of authorization enforcement on PATCH endpoints in /api/v2 REST API, letting unauthenticated attackers disable event and SNMP data collection, exploit requires attacker to access the web UI." url: https://panop.io/threat-heartbeat/CVE-2026-89054/ --- # CVE-2026-89054 OpenNMS Horizon - Broken Access Control OpenNMS Horizon contains a missing authorization vulnerability caused by lack of authorization enforcement on PATCH endpoints in /api/v2 REST API, letting unauthenticated attackers disable event and SNMP data collection, exploit requires attacker to access the web UI. CVSS base score 8.2 /10 High CISA KEV Not listed Public exploit None known Authentication Not required EPSS 0.51% chance of exploitation in 30 days [View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89054) ## Details Type Broken Access Control Impact Denial Of Service CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L Published 10 September 2026 Updated 15 October 2026 Weakness [CWE-862](https://cwe.mitre.org/data/definitions/862.html) ## Vendor fix Upgrade to Horizon 36.0.4 or newer. Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them. ## References - [https://nvd.nist.gov/vuln/detail/CVE-2026-89054](https://nvd.nist.gov/vuln/detail/CVE-2026-89054) - [https://github.com/OpenNMS/opennms/pull/8833](https://github.com/OpenNMS/opennms/pull/8833) [← All CVEs](https://panop.io/threat-heartbeat/) ## What this record can't tell you - Whether you run the affected software, and where - Whether an attacker can actually reach and exploit it - The misconfigurations that never get a CVE number - What it would cost the business, ranked into what to fix first Panop answers these inside your environment, for this CVE and every other finding. [Book a demo](https://panop.io/demo)