MEDIUM CVSS 5.3
Published: 2020-11-27

CVE-2020-29138

sagemcom f\@st_3486_router_firmware Security Advisory (CVE-2020-29138)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2020-29138 impacting sagemcom f\@st_3486_router_firmware. Evaluated with CVSS Base Score of 5.3 (MEDIUM).

Original NVD Description

Source: NIST NVD
Incorrect Access Control in the configuration backup path in SAGEMCOM F@ST3486 NET DOCSIS 3.0, software NET_4.109.0, allows remote unauthenticated users to download the router configuration file via the /backupsettings.conf URI, when any valid session is running.

📊 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
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
None (I:N)
No system modification impact
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product sagemcom / f\@st_3486_router_firmware
Affected Versions 4.109.0
Weakness Enumeration CWE-306

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-2020-29138 impacting sagemcom f\@st_3486_router_firmware.

⚡ Nuclei Detection Template (YAML) cve-2020-29138.yaml
id: cve-2020-29138

info:
  name: sagemcom f\@st_3486_router_firmware - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2020-29138 affecting sagemcom f\@st_3486_router_firmware.
    Evaluation: Incorrect Access Control in the configuration backup path in SAGEMCOM F@ST3486 NET DOCSIS 3.0, software NET_4.109.0, allows remote unauthenticated use...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2020-29138
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
    cvss-score: 5.3
    cve-id: CVE-2020-29138
    cwe-id: CWE-306
  tags: cve,cve-2020-29138,sagemcom,f\@st_3486_router_firmwar,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "f\@st_3486_router_firmware"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2020-29138.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2020-29138
# Target: sagemcom f\@st_3486_router_firmware | CVSS: 5.3 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2020-29138 (sagemcom f\@st_3486_router_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 sagemcom f\@st_3486_router_firmware scope (4.109.0).")
        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-2020-29138.sh
# Recommended Remediation & Patching Commands for CVE-2020-29138
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install f\@st_3486_router_firmwar 2>/dev/null || \
sudo dnf upgrade f\@st_3486_router_firmwar 2>/dev/null || \
sudo yum update f\@st_3486_router_firmwar

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i f\@st_3486_router_firmwar 2>/dev/null || rpm -qa | grep -i f\@st_3486_router_firmwar

# 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-2020-29138 in sagemcom f\@st_3486_router_firmware?

Review vendor-specific security notices and update sagemcom f\@st_3486_router_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-2020-29138?

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-2020-29138?

CVE-2020-29138 is classified with a CVSS 3.1 Base Score of 5.3 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.3
MEDIUM SEVERITY
CVE ID CVE-2020-29138
Weakness CWE-306
Vendor sagemcom
Product f\@st_3486_router_firmware
Published 2020-11-27
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N