MEDIUM CVSS 4.0
Published: 2026-05-14

CVE-2026-44430

lfprojects mcp_registry Security Advisory (CVE-2026-44430)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-44430 impacting lfprojects mcp_registry. Evaluated with CVSS Base Score of 4.0 (MEDIUM).

Original NVD Description

Source: NIST NVD
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.7, the Registry's HTTP-based namespace verification (POST /v0/auth/http, POST /v0.1/auth/http) uses safeDialContext (internal/api/handlers/v0/auth/http.go:67-110) to refuse dialling private/internal addresses when fetching the well-known public-key file from a publisher-supplied domain. The blocklist (isBlockedIP, lines 125-133) relies entirely on Go stdlib's IsLoopback / IsPrivate / IsLinkLocalUnicast / IsMulticast / IsUnspecified plus a manual CGNAT range. None of these cover IPv6 6to4 (2002::/16), NAT64 (64:ff9b::/96 and 64:ff9b:1::/48 per RFC 8215), or deprecated site-local (fec0::/10) — all of which encode arbitrary IPv4 in the address bits and tunnel to RFC1918 / cloud-metadata services on dual-stack / NAT64-enabled hosts. This vulnerability is fixed in 1.7.7.

📊 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
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product lfprojects / mcp_registry
Affected Versions *
Weakness Enumeration CWE-918

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-2026-44430 impacting lfprojects mcp_registry.

⚡ Nuclei Detection Template (YAML) cve-2026-44430.yaml
id: cve-2026-44430

info:
  name: lfprojects mcp_registry - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-44430 affecting lfprojects mcp_registry.
    Evaluation: The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. Prior to 1.7.7, the Registry's HTTP-based na...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-44430
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
    cvss-score: 4.0
    cve-id: CVE-2026-44430
    cwe-id: CWE-918
  tags: cve,cve-2026-44430,lfprojects,mcp_registry,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "mcp_registry"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-44430.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-44430
# Target: lfprojects mcp_registry | CVSS: 4.0 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-44430 (lfprojects mcp_registry)...")
    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 lfprojects mcp_registry 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-2026-44430.sh
# Recommended Remediation & Patching Commands for CVE-2026-44430
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install mcp_registry 2>/dev/null || \
sudo dnf upgrade mcp_registry 2>/dev/null || \
sudo yum update mcp_registry

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

# 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-2026-44430 in lfprojects mcp_registry?

Review vendor-specific security notices and update lfprojects mcp_registry 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-2026-44430?

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-2026-44430?

CVE-2026-44430 is classified with a CVSS 3.1 Base Score of 4.0 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.0
MEDIUM SEVERITY
CVE ID CVE-2026-44430
Weakness CWE-918
Vendor lfprojects
Product mcp_registry
Published 2026-05-14
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N