CVE-2026-19135
MediumCVSS 5.4Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
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.
Risk Assessment
An attacker can gain access to confidential information and compromise system integrity, potentially leading to severe compromise.
Recommendation
Upgrade to Meridian 2024.3.12, 2025.0.9 and Horizon 36.0.3 or newer. Also ensure systems are not directly accessible from the Internet.
Other vulnerabilities in OpenNMS
See all- CVE-2015-7856High
OpenNMS has a default password of 'rtc' for the rtc account, which makes it easier for remote attackers to obtain access by leveraging knowledge of the credentials.
- CVE-2026-19182Medium
An incorrect authorization check in the v2 Alarm REST API in OpenNMS Meridian and Horizon allows a low-privileged authenticated user (ROLE_REST) to acknowledge, escalate, or clear alarms recorded as an arbitrary username, and, when also assigned ROLE_READONLY, to modify alarm state despite the read-only restriction. A credential check is guarded by an inverted condition, so it never executes for a real (non-blank) username.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS