MEDIUM CVSS 5.9
Published: 2026-02-04

CVE-2026-1642

f5 nginx_gateway_fabric Security Advisory (CVE-2026-1642)
โ†— Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-1642 impacting f5 nginx_gateway_fabric. Evaluated with CVSS Base Score of 5.9 (MEDIUM).

Original NVD Description

Source: NIST NVD
A vulnerability exists in NGINX OSS and NGINX Plus when configured to proxy to upstream Transport Layer Security (TLS) servers. An attacker with a man-in-the-middle (MITM) position on the upstream server sideโ€”along with conditions beyond the attacker's controlโ€”may be able to inject plain text data into the response from an upstream proxied server.ย ย Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

๐Ÿ“Š CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
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
None (C:N)
No data confidentiality impact
Integrity
High (I:H)
Total modification of target system
Availability
None (A:N)
No system availability impact

๐ŸŽฏ Affected Versions Matrix

Affected Product f5 / nginx_gateway_fabric
Affected Versions *
Weakness Enumeration CWE-349

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-2026-1642 impacting f5 nginx_gateway_fabric.

โšก Nuclei Detection Template (YAML) cve-2026-1642.yaml
id: cve-2026-1642

info:
  name: f5 nginx_gateway_fabric - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-1642 affecting f5 nginx_gateway_fabric.
    Evaluation: A vulnerability exists in NGINX OSS and NGINX Plus when configured to proxy to upstream Transport Layer Security (TLS) servers. An attacker with a man...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-1642
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
    cvss-score: 5.9
    cve-id: CVE-2026-1642
    cwe-id: CWE-349
  tags: cve,cve-2026-1642,f5,nginx_gateway_fabric,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "nginx_gateway_fabric"
        part: body
๐Ÿ PoC Exploit & Verification Probe (Python 3) poc_cve-2026-1642.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-1642
# Target: f5 nginx_gateway_fabric | CVSS: 5.9 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-1642 (f5 nginx_gateway_fabric)...")
    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 f5 nginx_gateway_fabric 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)
๐Ÿ›ก๏ธ Quick Patch & Remediation Script (Bash) patch_cve-2026-1642.sh
# Recommended Remediation & Patching Commands for CVE-2026-1642
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install nginx_gateway_fabric 2>/dev/null || \
sudo dnf upgrade nginx_gateway_fabric 2>/dev/null || \
sudo yum update nginx_gateway_fabric

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

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

๐Ÿ›ก๏ธ 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.
โš ๏ธ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

๐Ÿ”— Verified Technical References

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

โ“ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-1642 in f5 nginx_gateway_fabric?

Review vendor-specific security notices and update f5 nginx_gateway_fabric 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-2026-1642?

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-2026-1642?

CVE-2026-1642 is classified with a CVSS 3.1 Base Score of 5.9 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.9
MEDIUM SEVERITY
CVE ID CVE-2026-1642
Weakness CWE-349
Vendor f5
Product nginx_gateway_fabric
Published 2026-02-04
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N