---
id: CVE-2026-19135
title: >-
  A JEXL expression sandbox bypass exists in multiple versions of OpenNMS
  Meridian and Horizon
summary: >-
  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 J…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-470
published: '2026-08-13'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:20:25.117'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-19135'
references:
  - url: 'https://github.com/OpenNMS/opennms/pull/8754'
    label: security@opennms.com
tags:
  - nvd
epss: 0.00288
epssPercentile: 0.19098
ingestedAt: '2026-09-08T20:10:03.156Z'
---

## Overview

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

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.