CVE-2026-127235: The OpenNMS Group Meridian · Cross-site Scripting
Affects The OpenNMS Group MeridianSource CVE Database V5
Not known to be exploited · CVSS 6.1 Medium · fixed in 2026.0.2 : update The OpenNMS Group Meridian when convenient.
Data as of 12 Nov 2026, 18:49 UTC
Thin evidence
One scorer or none| CNA (OpenNMS) | CVSS 3.1 | 6.1 |
|---|
- Patch
- Available – fixed in 2026.0.2, 2025.0.12, 2024.3.15 +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 12 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.
What to do
Upgrade Meridian to 2026.0.2, 2025.0.12 or 2024.3.15; Horizon to 36.0.6.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| The OpenNMS GroupMeridian | Affected
| Fixed in
|
| The OpenNMS GroupMeridian | Affected
| Fixed in
|
| The OpenNMS GroupMeridian | Affected
| Fixed in
|
| The OpenNMS GroupHorizon | Affected
| Fixed in
|
GitHubMeridianpkg:github/MeridianOther threats | Affected
| Fixed in
|
GitHubHorizonpkg:github/HorizonOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
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.