CVE-2026-19135

OpenNMS JEXL sandbox bypass in Measurements REST API allows ROLE_USER to load arbitrary classes

Published Aug 13, 2026 CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

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

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
OpenNMS
Published
Updated
Aug 13, 2026, 1:02 PM
Reserved
Aug 6, 2026, 4:14 PM
Status
Awaiting Analysis
Published
Aug 13, 2026, 5:17 AM
Modified
Sep 8, 2026, 7:20 PM