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.
AI Analysis
Technical Summary
This vulnerability involves unsafe reflection (CWE-470) due to a JEXL expression sandbox bypass in OpenNMS Meridian and Horizon. An authenticated user with low privileges can craft expressions submitted to the Measurements REST API that escape sandbox restrictions and load arbitrary Java classes on the server. This can lead to unauthorized access to confidential information and integrity compromise. The vulnerability affects Meridian versions 2024.1.0, 2025.0.0, and Horizon 36.0.0, with fixed versions being Meridian 2024.3.12, 2025.0.9, and Horizon 36.0.3 or newer.
Potential Impact
An attacker with low-privileged authenticated access can exploit this vulnerability to execute arbitrary Java code on the server by bypassing the JEXL sandbox. This can lead to unauthorized disclosure of confidential information and compromise of data integrity. There is no indication of availability impact. The CVSS score is 5.4 (medium severity), reflecting network attack vector, low attack complexity, and no user interaction required.
Mitigation Recommendations
Upgrade affected OpenNMS Meridian versions to 2024.3.12 or later, 2025.0.9 or later, and Horizon to 36.0.3 or later. Since these products are intended for private network deployment and not direct Internet exposure, ensure they remain protected behind appropriate network controls. Patch status is not explicitly stated as 'official-fix' in the vendor advisory, but the provided version upgrades are the recommended remediation. Check the vendor advisory for the latest guidance.
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
The OpenNMS Group
Meridian
The OpenNMS Group
Horizon
pkg:github/MeridianRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves unsafe reflection (CWE-470) due to a JEXL expression sandbox bypass in OpenNMS Meridian and Horizon. An authenticated user with low privileges can craft expressions submitted to the Measurements REST API that escape sandbox restrictions and load arbitrary Java classes on the server. This can lead to unauthorized access to confidential information and integrity compromise. The vulnerability affects Meridian versions 2024.1.0, 2025.0.0, and Horizon 36.0.0, with fixed versions being Meridian 2024.3.12, 2025.0.9, and Horizon 36.0.3 or newer.
Potential Impact
An attacker with low-privileged authenticated access can exploit this vulnerability to execute arbitrary Java code on the server by bypassing the JEXL sandbox. This can lead to unauthorized disclosure of confidential information and compromise of data integrity. There is no indication of availability impact. The CVSS score is 5.4 (medium severity), reflecting network attack vector, low attack complexity, and no user interaction required.
Mitigation Recommendations
Upgrade affected OpenNMS Meridian versions to 2024.3.12 or later, 2025.0.9 or later, and Horizon to 36.0.3 or later. Since these products are intended for private network deployment and not direct Internet exposure, ensure they remain protected behind appropriate network controls. Patch status is not explicitly stated as 'official-fix' in the vendor advisory, but the provided version upgrades are the recommended remediation. Check the vendor advisory for the latest guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- OpenNMS
- Date Reserved
- 2026-08-06T16:14:32.586Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a7d520ebf8831d539b45585
Added to database: 08/13/2026, 05:11:42 UTC
Last enriched: 08/13/2026, 05:30:15 UTC
Last updated: 09/27/2026, 13:47:43 UTC
Views: 72
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