MEDIUM CVSS 6.5
Published: 2026-05-07

CVE-2026-6736

github enterprise_server Security Advisory (CVE-2026-6736)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-6736 impacting github enterprise_server. Evaluated with CVSS Base Score of 6.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
An authentication bypass vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to create a local user account, bypassing the configured external identity provider. When external authentication was enabled, the signup endpoint did not properly enforce the authentication restriction, allowing account creation and session establishment without identity provider validation. The created account was limited to the default base permissions configured on the instance. Exploitation required network access to a GHES instance configured with an external authentication provider. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.2, 3.19.6, 3.18.9, 3.17.15, and 3.16.18.

📊 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
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product github / enterprise_server
Affected Versions *
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-2026-6736 impacting github enterprise_server.

⚡ Nuclei Detection Template (YAML) cve-2026-6736.yaml
id: cve-2026-6736

info:
  name: github enterprise_server - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-6736 affecting github enterprise_server.
    Evaluation: An authentication bypass vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to create a local user acco...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-6736
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
    cvss-score: 6.5
    cve-id: CVE-2026-6736
    cwe-id: CWE-306
  tags: cve,cve-2026-6736,github,enterprise_server,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "enterprise_server"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-6736.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-6736
# Target: github enterprise_server | 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-2026-6736 (github enterprise_server)...")
    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 github enterprise_server 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-2026-6736.sh
# Recommended Remediation & Patching Commands for CVE-2026-6736
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install enterprise_server 2>/dev/null || \
sudo dnf upgrade enterprise_server 2>/dev/null || \
sudo yum update enterprise_server

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

# 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-2026-6736 in github enterprise_server?

Review vendor-specific security notices and update github enterprise_server 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-2026-6736?

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-2026-6736?

CVE-2026-6736 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-2026-6736
Weakness CWE-306
Vendor github
Product enterprise_server
Published 2026-05-07
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N