CVE-2026-19135 PUBLISHED

OpenNMS JEXL sandbox bypass in Measurements REST API allows ROLE_USER to load arbitrary classes

Assigner: OpenNMS
Reserved: 06.08.2026 Published: 13.08.2026 Updated: 13.08.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CVSS Score: 5.4

Product Status

Vendor The OpenNMS Group
Product Meridian
Versions Default: unaffected
  • affected from 2024.1.0 to 2024.3.12 (excl.)
  • affected from 2025.0.0 to 2025.0.9 (excl.)
Vendor The OpenNMS Group
Product Horizon
Versions Default: unaffected
  • affected from 36.0.0 to 36.0.3 (excl.)

Solutions

Upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 or newer.

Credits

  • tinyb0y finder
  • Xanlar Agamalizade finder

References

Problem Types

  • CWE-470 Use of Externally-Controlled input to select classes or code ('unsafe reflection') CWE