CVE-2026-19135
Published:August 13, 2026
Updated:September 01, 2026
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.
Affected Packages
https://github.com/OpenNMS/opennms.git (GITHUB):
Affected version(s) >=meridian-foundation-2024.3.0-1 <meridian-foundation-2024.3.12-1Fix Suggestion:
Update to version meridian-foundation-2024.3.12-1https://github.com/OpenNMS/opennms.git (GITHUB):
Affected version(s) >=meridian-foundation-2025.0.0-1 <meridian-foundation-2025.0.9-1Fix Suggestion:
Update to version meridian-foundation-2025.0.9-1https://github.com/OpenNMS/opennms.git (GITHUB):
Affected version(s) >=opennms-36.0.0-1 <opennms-36.0.3-1Fix Suggestion:
Update to version opennms-36.0.3-1Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.4
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
EPSS
Base Score:
0.17