MEDIUM CVSS 6.5
Published: 2026-07-15

CVE-2026-52865

f5 nginx_ingress_controller Security Advisory (CVE-2026-52865)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-52865 impacting f5 nginx_ingress_controller. Evaluated with CVSS Base Score of 6.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
When NGINX Ingress Controller processes Ingress or TransportServer resources, an authenticated, remote attacker with permission to create or modify Ingress or TransportServer resources can cause the NGINX Ingress Controller process to terminate. Impact: The NGINX Ingress Controller control plane process terminates and enters a persistent crash loop while the malformed Ingress or TransportServer resource remains in the cluster. This vulnerability allows a remote, authenticated attacker with at least Ingress or TransportServer resource write access to cause a denial-of-service (DoS) on the NGINX Ingress Controller system. There is no data plane exposure; this is a control plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

📊 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
Low (PR:L)
Standard user access required
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
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product f5 / nginx_ingress_controller
Affected Versions *
Weakness Enumeration CWE-476

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-2026-52865 impacting f5 nginx_ingress_controller.

⚡ Nuclei Detection Template (YAML) cve-2026-52865.yaml
id: cve-2026-52865

info:
  name: f5 nginx_ingress_controller - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-52865 affecting f5 nginx_ingress_controller.
    Evaluation: When NGINX Ingress Controller processes Ingress or TransportServer resources, an authenticated, remote attacker with permission to create or modify In...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-52865
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
    cvss-score: 6.5
    cve-id: CVE-2026-52865
    cwe-id: CWE-476
  tags: cve,cve-2026-52865,f5,nginx_ingress_controller,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "nginx_ingress_controller"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-52865.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-52865
# Target: f5 nginx_ingress_controller | CVSS: 6.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-52865 (f5 nginx_ingress_controller)...")
    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_ingress_controller 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-2026-52865.sh
# Recommended Remediation & Patching Commands for CVE-2026-52865
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install nginx_ingress_controller 2>/dev/null || \
sudo dnf upgrade nginx_ingress_controller 2>/dev/null || \
sudo yum update nginx_ingress_controller

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

# 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-2026-52865 in f5 nginx_ingress_controller?

Review vendor-specific security notices and update f5 nginx_ingress_controller 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-2026-52865?

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-2026-52865?

CVE-2026-52865 is classified with a CVSS 3.1 Base Score of 6.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
6.5
MEDIUM SEVERITY
CVE ID CVE-2026-52865
Weakness CWE-476
Vendor f5
Product nginx_ingress_controller
Published 2026-07-15
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H