CVSS 3.1
6.1 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NCVE-2026-127235 OpenNMS reflected cross-site scripting in the web UI via request parameters
Medium (6.1) in the opennms group. EPSS 0.2% estimated probability of exploitation activity in the next 30 days.
On this page
A reflected cross-site scripting vulnerability exists in the web user interface of multiple versions of OpenNMS Meridian and Horizon. Several web UI pages copy request parameter values into the HTML response without correct contextual output encoding. A remote attacker can craft a link that runs arbitrary JavaScript in the OpenNMS origin when an authenticated user opens it. The script runs in the victim's browser with the victim's session, so the attacker can read page data and send same-origin requests as the victim. The fix encodes the affected request values. On pages that use AngularJS, the fix also stops client-side template evaluation of the reflected values.
The solution is to upgrade to Meridian 2024.3.15, 2025.0.12, 2026.0.2 and Horizon 36.0.6 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.
Severity
- EPSS
- 0.2% estimated probability of exploitation activity in the next 30 days; 7th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-79 Improper Neutralization of Input During Web Page Generation (Cross-site Scripting)
- OWASP Top 10
- A05:2025 Injection
- Published
- Modified
- Assigned by
- OpenNMS (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
- the opennms group:horizon
- the opennms group:meridian
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| The OpenNMS Group Meridian | from 2024.1.0 before 2024.3.15 |
| The OpenNMS Group Meridian | from 2025.0.0 before 2025.0.12 |
| The OpenNMS Group Meridian | from 2026.0.0 before 2026.0.2 |
| The OpenNMS Group Horizon | from 36.0.0 before 36.0.6 |
Attack patterns (CAPEC)
- CAPEC-63 Cross-Site Scripting (XSS) Likelihood: High · Severity: Very High
- CAPEC-85 AJAX Footprinting Likelihood: High · Severity: Low
- CAPEC-209 XSS Using MIME Type Mismatch Severity: Medium
- CAPEC-588 DOM-Based XSS Likelihood: High · Severity: Very High
- CAPEC-591 Reflected XSS Likelihood: High · Severity: Very High
- CAPEC-592 Stored XSS Likelihood: High · Severity: Very High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.