CVE-2026-111235
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.
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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.
CVSS
- Base score
- 9.1
- Version
- 3.1
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.38 %
- Percentile among all scored CVEs
- 30
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
ATT&CK techniques
How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.
- Exploitation
T1190Exploit Public-Facing Applicationinitial access95 % - Primary impact
T1565Data Manipulationimpact85 % - Secondary impact
T1213Data from Information Repositoriescollection70 %
CVSS AV:N/PR:N/UI:N y la descripción indica acceso remoto sin autenticación a la API REST; inyección de eventos y modificación de recursos sustentan T1565, y lectura inventario T1213.
Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.
ATT&CK mitigations that cover these techniques
Affected technologies (2)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
CWEs
- CWE-204, CWE-862, CWE-863
References
Show 1 references
Raw JSON (NVD)
Show
{
"id": "CVE-2026-111235",
"cveTags": [],
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"version": "2.0.3",
"timestamp": "2026-10-16T19:59:23.754367Z"
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"affected": [
{
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"affectedData": [
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"vendor": "The OpenNMS Group",
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"value": "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.\n\n\n\nThe 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."
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"lastModified": "2026-10-16T20:17:19.620",
"sourceIdentifier": "security@opennms.com"
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