HIGH CVSS 7.4
Published: 2020-12-14

CVE-2020-5665

mitsubishielectric melsec_iq-f_fx5u_cpu_firmware Security Advisory (CVE-2020-5665)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2020-5665 impacting mitsubishielectric melsec_iq-f_fx5u_cpu_firmware. Evaluated with CVSS Base Score of 7.4 (HIGH).

Original NVD Description

Source: NIST NVD
Improper check or handling of exceptional conditions in MELSEC iQ-F series FX5U(C) CPU unit firmware version 1.060 and earlier allows an attacker to cause a denial-of-service (DoS) condition on program execution and communication by sending a specially crafted ARP packet.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Adjacent (AV:A)
Requires shared subnet / local network access
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product mitsubishielectric / melsec_iq-f_fx5u_cpu_firmware
Affected Versions *
Weakness Enumeration NVD-CWE-noinfo

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-2020-5665 impacting mitsubishielectric melsec_iq-f_fx5u_cpu_firmware.

⚡ Nuclei Detection Template (YAML) cve-2020-5665.yaml
id: cve-2020-5665

info:
  name: mitsubishielectric melsec_iq-f_fx5u_cpu_firmware - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2020-5665 affecting mitsubishielectric melsec_iq-f_fx5u_cpu_firmware.
    Evaluation: Improper check or handling of exceptional conditions in MELSEC iQ-F series FX5U(C) CPU unit firmware version 1.060 and earlier allows an attacker to c...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2020-5665
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
    cvss-score: 7.4
    cve-id: CVE-2020-5665
    cwe-id: NVD-CWE-noinfo
  tags: cve,cve-2020-5665,mitsubishielectric,melsec_iq-f_fx5u_cpu_firm,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "melsec_iq-f_fx5u_cpu_firmware"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2020-5665.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2020-5665
# Target: mitsubishielectric melsec_iq-f_fx5u_cpu_firmware | CVSS: 7.4 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2020-5665 (mitsubishielectric melsec_iq-f_fx5u_cpu_firmware)...")
    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 mitsubishielectric melsec_iq-f_fx5u_cpu_firmware 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-2020-5665.sh
# Recommended Remediation & Patching Commands for CVE-2020-5665
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install melsec_iq-f_fx5u_cpu_firm 2>/dev/null || \
sudo dnf upgrade melsec_iq-f_fx5u_cpu_firm 2>/dev/null || \
sudo yum update melsec_iq-f_fx5u_cpu_firm

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i melsec_iq-f_fx5u_cpu_firm 2>/dev/null || rpm -qa | grep -i melsec_iq-f_fx5u_cpu_firm

# 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-2020-5665 in mitsubishielectric melsec_iq-f_fx5u_cpu_firmware?

Review vendor-specific security notices and update mitsubishielectric melsec_iq-f_fx5u_cpu_firmware 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-2020-5665?

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-2020-5665?

CVE-2020-5665 is classified with a CVSS 3.1 Base Score of 7.4 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.4
HIGH SEVERITY
CVE ID CVE-2020-5665
Weakness NVD-CWE-noinfo
Vendor mitsubishielectric
Product melsec_iq-f_fx5u_cpu_firmware
Published 2020-12-14
Vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H