MEDIUM CVSS 4.7
Published: 2026-04-02

CVE-2026-5339

tenda g103_firmware Security Advisory (CVE-2026-5339)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-5339 impacting tenda g103_firmware. Evaluated with CVSS Base Score of 4.7 (MEDIUM).

Original NVD Description

Source: NIST NVD
A vulnerability was detected in Tenda G103 1.0.0.5. The impacted element is the function action_set_net_settings of the file gpon.lua of the component Setting Handler. Performing a manipulation of the argument authLoid/authLoidPassword/authPassword/authSerialNo/authType/oltType/usVlanId/usVlanPriority results in command injection. It is possible to initiate the attack remotely. The exploit is now public and may be used.

📊 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
High (PR:H)
Administrative credentials required
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
Low (I:L)
Partial data modification possible
Availability
Low (A:L)
Partial service performance degradation

🎯 Affected Versions Matrix

Affected Product tenda / g103_firmware
Affected Versions 1.0.0.5
Weakness Enumeration CWE-74

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-2026-5339 impacting tenda g103_firmware.

⚡ Nuclei Detection Template (YAML) cve-2026-5339.yaml
id: cve-2026-5339

info:
  name: tenda g103_firmware - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-5339 affecting tenda g103_firmware.
    Evaluation: A vulnerability was detected in Tenda G103 1.0.0.5. The impacted element is the function action_set_net_settings of the file gpon.lua of the component...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-5339
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L
    cvss-score: 4.7
    cve-id: CVE-2026-5339
    cwe-id: CWE-74
  tags: cve,cve-2026-5339,tenda,g103_firmware,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "g103_firmware"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-5339.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-5339
# Target: tenda g103_firmware | CVSS: 4.7 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-5339 (tenda g103_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 tenda g103_firmware scope (1.0.0.5).")
        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-2026-5339.sh
# Recommended Remediation & Patching Commands for CVE-2026-5339
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install g103_firmware 2>/dev/null || \
sudo dnf upgrade g103_firmware 2>/dev/null || \
sudo yum update g103_firmware

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i g103_firmware 2>/dev/null || rpm -qa | grep -i g103_firmware

# 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.

🔗 Verified Technical References

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-5339 in tenda g103_firmware?

Review vendor-specific security notices and update tenda g103_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-2026-5339?

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-2026-5339?

CVE-2026-5339 is classified with a CVSS 3.1 Base Score of 4.7 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.7
MEDIUM SEVERITY
CVE ID CVE-2026-5339
Weakness CWE-74
Vendor tenda
Product g103_firmware
Published 2026-04-02
Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L