MEDIUM CVSS 4.3
Published: 2026-05-04

CVE-2026-42085

openc3 cosmos Security Advisory (CVE-2026-42085)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-42085 impacting openc3 cosmos. Evaluated with CVSS Base Score of 4.3 (MEDIUM).

Original NVD Description

Source: NIST NVD
OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to versions 6.10.5 and 7.0.0-rc3, OpenC3 COSMOS contains a design flaw in the save_tool_config() function that allows saving tool configuration files at arbitrary locations inside the shared /plugins directory tree by supplying crafted configuration filenames. Although the implementation sufficiently mitigates standard path traversal attacks, by canonicalizing filename to an absolute path, all plugins share this same root directory. That enables users to create arbitrary file structures and overwrite existing configuration files within the shared /plugins directory. This issue has been patched in versions 6.10.5 and 7.0.0-rc3.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product openc3 / cosmos
Affected Versions *
Weakness Enumeration CWE-23

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-42085 impacting openc3 cosmos.

⚡ Nuclei Detection Template (YAML) cve-2026-42085.yaml
id: cve-2026-42085

info:
  name: openc3 cosmos - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-42085 affecting openc3 cosmos.
    Evaluation: OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to versions 6.10.5 and 7...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-42085
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
    cvss-score: 4.3
    cve-id: CVE-2026-42085
    cwe-id: CWE-23
  tags: cve,cve-2026-42085,openc3,cosmos,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "cosmos"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-42085.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-42085
# Target: openc3 cosmos | CVSS: 4.3 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-42085 (openc3 cosmos)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against openc3 cosmos scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-42085.sh
# Recommended Remediation & Patching Commands for CVE-2026-42085
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install cosmos 2>/dev/null || \
sudo dnf upgrade cosmos 2>/dev/null || \
sudo yum update cosmos

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i cosmos 2>/dev/null || rpm -qa | grep -i cosmos

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-42085 in openc3 cosmos?

Review vendor-specific security notices and update openc3 cosmos packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-42085?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-42085?

CVE-2026-42085 is classified with a CVSS 3.1 Base Score of 4.3 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.3
MEDIUM SEVERITY
CVE ID CVE-2026-42085
Weakness CWE-23
Vendor openc3
Product cosmos
Published 2026-05-04
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N