CVE
The OpenNMS Group Meridian reflected cross-site scripting in web UI
- Exploited
- No known exploitation
- Fix
- Fixed in Meridian 2024.3.15, 2025.0.12, 2026.0.2 · Horizon 36.0.6
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: Meridian 2024.3.15, 2025.0.12, 2026.0.2 · Horizon 36.0.6.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.18% · 7th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 13/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Reflected cross-site scripting in the web interface of OpenNMS Meridian and OpenNMS Horizon lets a remote attacker run JavaScript in a user's browser, within the OpenNMS site, after the user opens a crafted link while logged in. The script can read page data and act as the user, and the attack requires the user to open the link.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original 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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure7/25Reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity6.1/10CVSS 6.1
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 28 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: Meridian 2024.3.15, 2025.0.12, 2026.0.2 · Horizon 36.0.6.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-127235 (OpenNMS reflected cross-site scripting in the web UI via request parameters), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-127235 (entry last updated 2026-11-12):
Affected:
- The OpenNMS Group Meridian: from 2024.1.0, fixed in 2024.3.15; from 2025.0.0, fixed in 2025.0.12; from 2026.0.0, fixed in 2026.0.2
- The OpenNMS Group Horizon: from 36.0.0, fixed in 36.0.6
Fixed versions: 2024.3.15, 2025.0.12, 2026.0.2, 36.0.6.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-127235 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-127235 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/OpenNMS/opennms/pull/9066
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-127235
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-127235"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- The OpenNMS Group Meridian
From 2024.1.0 · fixed in 2024.3.15; From 2025.0.0 · fixed in 2025.0.12; From 2026.0.0 · fixed in 2026.0.2
- The OpenNMS Group Horizon
From 36.0.0 · fixed in 36.0.6
Evidence 3
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 1
- Patch
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-127235
Is CVE-2026-127235 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-127235?
Meridian: from 2024.1.0 before 2024.3.15; from 2025.0.0 before 2025.0.12; from 2026.0.0 before 2026.0.2. Horizon: from 36.0.0 before 36.0.6.Source: cve.now feed data
How do I fix CVE-2026-127235?
Upgrade to a fixed version: Meridian 2024.3.15, 2025.0.12, 2026.0.2 · Horizon 36.0.6.Source: cve.now feed data