Vulnerability in The Opennms Group Horizon
CVE-2026-19135
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- The Opennms Group Horizon — versions 36.0.0
- The Opennms Group Meridian — versions 2024.1.0, 2025.0.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-19135?
- CVE-2026-19135 is a medium-severity vulnerability in The Opennms Group Horizon, classified under Use of Externally-Controlled Input to Select Classes or Code (Unsafe Reflection). CVSS score: 5.4/10. Published 2026-08-13.
- How severe is CVE-2026-19135?
- Medium severity. CVSS v3 base score is 5.4 out of 10.