CVE-2026-111235 OpenNMS Meridian & Horizon - Authorization Bypass

OpenNMS Meridian and Horizon contain an authorization bypass caused by case-sensitive HTTP method checks missing terminal deny rules in REST API Spring Security filter chains, letting remote unauthenticated attackers read and modify resources, exploit requires sending requests with non-canonical HTTP methods.

CVSS base score 9.1 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Broken Access Control, Data Tampering, Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
15 October 2026
Updated
16 October 2026
Weakness
CWE-204

Vendor fix

Upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1 and Horizon 36.0.5 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

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