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VulnerabilityPublished

CVE-2026-127235: Reflected Cross-site Scripting Vulnerability Exists

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Authoritative record:CVE-2026-127235· Medium 6.1

Not known to be exploited · CVSS 6.1 Medium · fixed in 2026.0.2 : update Meridian when convenient.

Data as of 12 Nov 2026, 22:33 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (OpenNMS)CVSS 3.16.1
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
The OpenNMS GroupMeridianAffected
  • >=2026.0.0 <2026.0.2
Fixed in
  • 2026.0.2
The OpenNMS GroupMeridianAffected
  • >=2025.0.0 <2025.0.12
Fixed in
  • 2025.0.12
The OpenNMS GroupMeridianAffected
  • >=2024.1.0 <2024.3.15
Fixed in
  • 2024.3.15
The OpenNMS GroupHorizonAffected
  • >=36.0.0 <36.0.6
Fixed in
  • 36.0.6
GitHubMeridianpkg:github/MeridianOther threatsAffected
  • >=2024.1.0 <2024.3.15
  • >=2025.0.0 <2025.0.12
  • >=2026.0.0 <2026.0.2
Fixed in
  • 2024.3.15
  • 2025.0.12
  • 2026.0.2
GitHubHorizonpkg:github/HorizonOther threatsAffected
  • >=36.0.0 <36.0.6
Fixed in
  • 36.0.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade affected OpenNMS Meridian installations to version 2024.3.15, 2025.0.12, 2026.0.2 or later, and Horizon installations to version 36.0.6 or later. These versions include fixes that properly encode reflected request parameters and prevent unsafe client-side template evaluation. Additionally, ensure that OpenNMS web interfaces are not directly accessible from the Internet, as recommended by the installation guidelines.

Description

A reflected cross-site scripting (XSS) vulnerability exists in the web user interface of multiple versions of OpenNMS Meridian and Horizon. The flaw occurs because several web UI pages improperly handle request parameters, allowing an attacker to inject and execute arbitrary JavaScript in the context of an authenticated user's browser session. This enables the attacker to read page data and perform actions with the victim's privileges. The vulnerability is fixed by encoding affected request values and preventing client-side template evaluation on AngularJS pages. Upgrading to Meridian 2024.3.15, 2025.0.12, 2026.0.2 or Horizon 36.0.6 or newer resolves the issue. These products are intended for private network use and should not be exposed directly to the Internet.

References

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