A JEXL expression sandbox bypass exists in multiple versions of OpenNMS Meridian and Horizon. A low-privileged authenticated user can submit a crafted expression to the Measurements REST API that escapes the sandbox and loads arbitrary Java classes on the server. This can potentially allow an attacker to gain access to confidential information and compromise integrity.

The solution is to upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 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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Advisories

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Fixes

Solution

Upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 or newer.


Workaround

No workaround given by the vendor.

History

Thu, 13 Aug 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 13 Aug 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Opennms
Opennms horizon
Opennms meridian
Vendors & Products Opennms
Opennms horizon
Opennms meridian

Thu, 13 Aug 2026 05:15:00 +0000

Type Values Removed Values Added
Description A JEXL expression sandbox bypass exists in multiple versions of OpenNMS Meridian and Horizon. A low-privileged authenticated user can submit a crafted expression to the Measurements REST API that escapes the sandbox and loads arbitrary Java classes on the server. This can potentially allow an attacker to gain access to confidential information and compromise integrity. The solution is to upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 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.
Title OpenNMS JEXL sandbox bypass in Measurements REST API allows ROLE_USER to load arbitrary classes
Weaknesses CWE-470
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: OpenNMS

Published:

Updated: 2026-08-13T13:02:21.227Z

Reserved: 2026-08-06T16:14:32.586Z

Link: CVE-2026-19135

cve-icon Vulnrichment

Updated: 2026-08-13T13:02:16.485Z

cve-icon NVD

Status : Received

Published: 2026-08-13T05:17:22.750

Modified: 2026-08-13T13:17:48.510

Link: CVE-2026-19135

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-13T09:47:22Z

Weaknesses