CVE-2026-19135 OpenNMS JEXL sandbox bypass in Measurements REST API allows ROLE_USER to load arbitrary classes
Low-privileged users can bypass JEXL sandbox in OpenNMS Measurements API to load arbitrary classes, risking data confidentiality and integrity.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19135?
CVE-2026-19135 is a medium-severity code injection vulnerability in The OpenNMS Group Horizon, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
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.
Weakness: CWE-470
Which versions are affected by CVE-2026-19135?
How do I fix CVE-2026-19135?
No fix has been published for CVE-2026-19135 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-19135 being exploited?
There is no known exploitation of CVE-2026-19135 in the wild and no public exploit code.
Sources
Also known as GHSA-q2r2-4mh9-4268, UBUNTU-CVE-2026-19135.