OpenNMS REST authorization bypass via non-canonical HTTP method

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-111235
StatePUBLISHED
AssignerOpenNMS
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-15 19:17:36 UTC
Updated2026-10-15 19:17:36 UTC
DescriptionAn 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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem Types: CWE-204 | CWE-862 | CWE-863 | CWE-862 CWE-862 Missing Authorization | CWE-863 CWE-863 Incorrect Authorization | CWE-204 CWE-204 Observable Response Discrepancy

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1CNACVSS9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The OpenNMS Group Meridian affected 2024.1.0 2024.3.14 maven Not specified
CNA The OpenNMS Group Meridian affected 2025.0.0 2025.0.11 maven Not specified
CNA The OpenNMS Group Meridian affected 2026.0.0 2026.0.1 maven Not specified
CNA The OpenNMS Group Horizon affected 36.0.0 36.0.5 maven Not specified

References

ReferenceSourceLinkTags
github.com/OpenNMS/opennms/pull/8934 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Pongsathon Sirithanyakul (en)

CNA: Warunyou Sunpachit (en)

CNA: Khamolwan hnunainam (en)

Additional Advisory Data

Solutions

CNA: Upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1 and Horizon 36.0.5 or newer.

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