CVE-2026-19596
MediumCVSS 5.9Exploitation Probability (EPSS)
Low risk12th percentile - higher than 12% of all known CVEs
Summary
An XML External Entity (XXE) vulnerability exists in the XML collector of multiple versions of OpenNMS Meridian and Horizon. When OpenNMS collects XML from a source whose response is attacker-controlled (for example a compromised monitored host or an HTTP man-in-the-middle position), the collector's XML parser resolves external entities and external DTDs. This allows an attacker to read files accessible to the OpenNMS service account, including database credentials, and to induce out-of-band requests.
Risk Assessment
An attacker can read sensitive files, including database credentials, and perform out-of-band requests, potentially leading to further system compromise.
Recommendation
Upgrade OpenNMS Meridian to version 2024.3.13 or 2025.0.10, and Horizon to version 36.0.4 or newer, and ensure systems are not directly accessible from the Internet.
Other vulnerabilities in OpenNMS Meridian and Horizon
See all- CVE-2026-111235Critical
An authorization bypass vulnerability exists in the REST API of multiple versions of OpenNMS Meridian and Horizon. The /rest/** Spring Security filter chains authorize requests with intercept-url rules that name the HTTP method as an uppercase token, compare the method case-sensitively, and have no terminal deny rule. A request that uses a non-canonical (for example lowercase) method token matches no rule and is processed without authentication. A remote, unauthenticated attacker can read the monitored inventory and can create, modify, or delete resources through the REST API, which includes injecting events to fabricate or suppress alarms. The /rest/alarms chain has the same missing deny rule and discloses whether an alarm exists through a difference in the response. The fix adds a terminal deny rule to each REST filter chain. The solution is to upgrade to Meridian 2024.3.14, 2025.0.11, 2026.0.1 and Horizon 36.0.5 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.
- CVE-2026-89089Medium
A SQL injection vulnerability exists in the JasperReports-based reporting feature of multiple versions of OpenNMS Meridian and Horizon. A low-privileged authenticated user (ROLE_USER) can run the shipped, default-enabled online reports "Maintenance contracts expired" and "Maintenance contracts strategy" via the reporting REST API (POST /rest/reports/{id}) and supply a DATE_FORMAT parameter that the report templates substitute literally, un-escaped, into their SQL queries, allowing arbitrary SQL execution and reading of arbitrary data including database-stored secrets.
Original NVD description (English source)
An XML External Entity (XXE) vulnerability exists in the XML collector of multiple versions of OpenNMS Meridian and Horizon. When OpenNMS collects XML from a source whose response is attacker-controlled (for example a compromised monitored host or an HTTP man-in-the-middle position), the collector's XML parser resolves external entities and external DTDs. This allows an attacker to read files accessible to the OpenNMS service account, including database credentials, and to induce out-of-band requests. The solution is to upgrade to Meridian 2024.3.13, 2025.0.10 and Horizon 36.0.4 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