CVE-2026-111235
9.1CriticalPublished 15 Oct 2026 · NVD status: Awaiting Analysis · AI triage by gemini-3.8-flash
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Impact
- High impact on confidentiality, integrity
- Weakness
- CWE-204, CWE-862, CWE-863
Impact
Unauthenticated remote attackers can read inventory data, manipulate resources, and inject or suppress alarms via the REST API. They only need network access to the OpenNMS REST endpoints.
Root cause
Spring Security intercept-url filters perform case-sensitive matching on uppercase HTTP methods and lack a terminal deny rule, allowing requests with lowercase method names to bypass authentication.
Affected systems
OpenNMS Meridian versions prior to 2024.3.14, 2025.0.11, and 2026.0.1; OpenNMS Horizon versions prior to 36.0.5.
CVSS v3.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Fix & remediation
Upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1, or Horizon 36.0.5 or newer. If you cannot patch immediately, block external access to the REST API endpoints (/rest/**) or restrict instance access to internal networks.
AI-suggested. Run it in staging first and check it against the vendor advisory. Why?
NVD description
An authorization bypass vulnerability exists in the REST API of multiple versions of OpenNMS Meridian and Horizon. The /rest/** Spring Security filter chains authorize requests with intercept-url rules that name the HTTP method as an uppercase token, compare the method case-sensitively, and have no terminal deny rule. A request that uses a non-canonical (for example lowercase) method token matches no rule and is processed without authentication. A remote, unauthenticated attacker can read the monitored inventory and can create, modify, or delete resources through the REST API, which includes injecting events to fabricate or suppress alarms. The /rest/alarms chain has the same missing deny rule and discloses whether an alarm exists through a difference in the response. The fix adds a terminal deny rule to each REST filter chain. The solution is to upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1 and Horizon 36.0.5 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.