Vulnerability · Published Aug 13, 2026 · Assigned by OpenNMS
CVE-2026-19135OpenNMS JEXL sandbox bypass in Measurements REST API allows ROLE_USER to load arbitrary classes
Medium 5.4
In plain English
A medium-severity security flaw in Horizon from The OpenNMS Group. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities).
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | horizon | no fix listed | UBUNTU-CVE-2026-19135 |
| Ubuntu:24.04:LTS | horizon | no fix listed | UBUNTU-CVE-2026-19135 |
| Ubuntu:26.04:LTS | horizon | no fix listed | UBUNTU-CVE-2026-19135 |
| Ubuntu:26.10 | horizon | no fix listed | UBUNTU-CVE-2026-19135 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| The OpenNMS Group | Meridian | 2024.1.0 – before 2024.3.122025.0.0 – before 2025.0.9 |
| The OpenNMS Group | Horizon | 36.0.0 – before 36.0.3 |
Weakness: CWE-470 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N