CVE-2026-19135: CWE-470 Use of Externally-Controlled input to select classes or code ('unsafe reflection') in The OpenNMS Group Meridian
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.
CVE-2026-19135: CWE-470 Use of Externally-Controlled input to select classes or code ('unsafe reflection') in The OpenNMS Group Meridian
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.
CVSS v3.1
Score 5.4medium
Affected software
pkg:github/MeridianRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- OpenNMS
- Date Reserved
- 2026-08-06T16:14:32.586Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a7d520ebf8831d539b45585
Added to database: 08/13/2026, 05:11:42 UTC
Last updated: 08/13/2026, 05:11:42 UTC
Views: 1
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