MEDIUM CVSS 5.4
Published: 2026-01-08

CVE-2026-21639

ui airmax_ac_firmware Security Advisory (CVE-2026-21639)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-21639 impacting ui airmax_ac_firmware. Evaluated with CVSS Base Score of 5.4 (MEDIUM).

Original NVD Description

Source: NIST NVD
A malicious actor in Wi-Fi range of the affected product could leverage a vulnerability in the airMAX Wireless Protocol to achieve a remote code execution (RCE) within the affected product. Affected Products: airMAX AC (Version 8.7.20 and earlier) airMAX M (Version 6.3.22 and earlier) airFiber AF60-XG (Version 1.2.2 and earlier) airFiber AF60 (Version 2.6.7 and earlier) Mitigation: Update your airMAX AC to Version 8.7.21 or later. Update your airMAX M to Version 6.3.24 or later. Update your airFiber AF60-XG to Version 1.2.3 or later. Update your airFiber AF60 to Version 2.6.8 or later.

📊 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
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product ui / airmax_ac_firmware
Affected Versions *
Weakness Enumeration CWE-77

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-2026-21639 impacting ui airmax_ac_firmware.

⚡ Nuclei Detection Template (YAML) cve-2026-21639.yaml
id: cve-2026-21639

info:
  name: ui airmax_ac_firmware - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-21639 affecting ui airmax_ac_firmware.
    Evaluation: A malicious actor in Wi-Fi range of the affected product could leverage a vulnerability in the airMAX Wireless Protocol to achieve a remote code execu...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-21639
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
    cvss-score: 5.4
    cve-id: CVE-2026-21639
    cwe-id: CWE-77
  tags: cve,cve-2026-21639,ui,airmax_ac_firmware,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "airmax_ac_firmware"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-21639.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-21639
# Target: ui airmax_ac_firmware | CVSS: 5.4 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-21639 (ui airmax_ac_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 ui airmax_ac_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-2026-21639.sh
# Recommended Remediation & Patching Commands for CVE-2026-21639
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install airmax_ac_firmware 2>/dev/null || \
sudo dnf upgrade airmax_ac_firmware 2>/dev/null || \
sudo yum update airmax_ac_firmware

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

Authorities
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-21639 in ui airmax_ac_firmware?

Review vendor-specific security notices and update ui airmax_ac_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-2026-21639?

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-2026-21639?

CVE-2026-21639 is classified with a CVSS 3.1 Base Score of 5.4 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.4
MEDIUM SEVERITY
CVE ID CVE-2026-21639
Weakness CWE-77
Vendor ui
Product airmax_ac_firmware
Published 2026-01-08
Vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N