CVE-2023-0871: Opennms Horizon

Medium severity, CVSS 6.1. EPSS: 0.5% chance of exploitation in the next 30 days.

XXE injection in /rtc/post/ endpoint in OpenMNS Horizon 31.0.8 and versions earlier than 32.0.2 on multiple platforms is vulnerable to XML external entity (XXE) injection, which can be used for instance to force Horizon to make arbitrary HTTP requests to internal and external services. The solution is to upgrade to Meridian 2023.1.6, 2022.1.19, 2021.1.30, 2020.1.38 or Horizon 32.0.2 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. OpenNMS thanks Erik Wynter and Moshe Apelbaum for reporting this issue.

Affected products

• Opennms Horizon: from 32.0.0, before 32.0.2 (fixed in 32.0.2); version 31.0.8 only
• Opennms Meridian: from 2020.0.0, before 2020.1.38 (fixed in 2020.1.38); from 2021.0.0, before 2021.1.30 (fixed in 2021.1.30); from 2022.1.0, before 2022.1.9 (fixed in 2022.1.9); from 2023.0.0, before 2023.1.6 (fixed in 2023.1.6)

Published 2023-08-11. Last modified 2026-06-17.