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VulnerabilityPublished

CVE-2026-127236: The OpenNMS Group Meridian · Argument Injection

Affects The OpenNMS Group MeridianSource CVE Database V5

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Not known to be exploited · CVSS 5.4 Medium · fixed in 2026.0.2 : update The OpenNMS Group Meridian when convenient.

Data as of 12 Nov 2026, 18:49 UTC

CVSS 3.1 base score
5.4Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (OpenNMS)CVSS 3.15.4
Patch
Available – fixed in 2026.0.2, 2025.0.12, 2024.3.15 +1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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.

Description

An argument injection vulnerability exists in the ad-hoc RRD graph feature of multiple versions of OpenNMS Meridian and Horizon. The ad-hoc graph endpoint (GET /graph/graph.png?adhoc=true) copies request parameters into the rrdtool command line without validation. A low-privileged authenticated user (ROLE_USER or ROLE_DASHBOARD) can insert extra rrdtool arguments. An injected --daemon argument makes the server connect to an attacker-chosen address, which is a server-side request forgery. An injected DEF statement reads a local RRD file by absolute path. The command runs through exec with an argument array and no shell, so arbitrary operating system command execution is not possible. The fix validates the ad-hoc graph parameters against allowlists. 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.

References

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