Answer in brief
CVE-2026-127236 records a Medium severity (CVSS 5.4) vulnerability in OpenNMS argument injection in ad-hoc RRD graphs. The current sources do not mark it as known exploited. The current feed maps The OpenNMS Group/Horizon (generic), The OpenNMS Group/Meridian (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps The OpenNMS Group/Horizon (generic), The OpenNMS Group/Meridian (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| The OpenNMS Group/Horizongeneric | >=36.0.0 <36.0.6 | 36.0.6 |
| The OpenNMS Group/Meridiangeneric | >=2024.1.0 <2024.3.15 || >=2025.0.0 <2025.0.12 || >=2026.0.0 <2026.0.2 | 2024.3.15, 2025.0.12, 2026.0.2 |
Published upstream
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 12, 2026
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.
Quoted source text, attributed separately from HOL analysis.