CVE-2025-29927 - Next.js Middleware Authorization Bypass POC

⚠️ Legal Disclaimer: This tool is intended for security research, authorized penetration testing, and educational purposes only. Using this tool against target systems without explicit permission is illegal and unethical.

📋 Overview

CVE-2025-29927 is a critical security vulnerability in Next.js that allows attackers to bypass middleware-based authorization controls by exploiting improper handling of the x-middleware-subrequest header.

🎯 Vulnerability Details

🔍 Technical Details

Root Cause: Next.js middleware mishandles the x-middleware-subrequest header, treating requests with this header as internal trusted sub-requests, thereby bypassing authorization checks.

Impact: Attackers can access protected routes (e.g., /admin, /api/sensitive) without authentication.

🚀 Features

• ✅ Single-file Python exploitation tool
• ✅ Automated vulnerability detection
• ✅ Batch scanning support
• ✅ Docker-based vulnerable environment
• ✅ Detailed logging and output
• ✅ No external dependencies (only requests)

📦 Installation

# Clone the repository
git clone https://github.com/hujiaozhuzhu/CVE-2025-29927-POC.git
cd CVE-2025-29927-POC

# Install dependencies
pip install -r requirements.txt

🎯 Usage

Quick Start (Exploit a Single Target)

python exploit/cve_2025_29927.py -u http://127.0.0.1:3000

Advanced Options

# Custom admin path
python exploit/cve_2025_29927.py -u http://target.com -p /admin

# Verbose output
python exploit/cve_2025_29927.py -u http://target.com -v

# Save results to a file
python exploit/cve_2025_29927.py -u http://target.com -o results.txt

Batch Scanning

# Scan multiple targets from a file
python exploit/batch_scanner.py -f targets.txt

# Scan an IP range
python exploit/batch_scanner.py --range 192.168.1.0-255

🏗️ Setup Vulnerable Environment

Using Docker (Recommended)

cd target
docker-compose up -d

Access the vulnerable application: http://localhost:3000

Manual Setup

cd target
npm install
npm run dev

📊 Vulnerability Detection Flow

1. Normal Request: Send a GET request without the exploit header

   • Expected: 302/401/403 (blocked by middleware)

2. Exploit Request: Send a GET request with x-middleware-subrequest: 1

   • Expected: 200 (bypasses middleware)
   • Success: Response contains admin content

🛡️ Mitigation & Defense

Immediate Actions

1. Upgrade Next.js

   root@kitploit:~

   npm install next@latest
   # or
   npm install [email protected]
   

2. Block Vulnerable Header in Reverse Proxy

   root@kitploit:~

   location / {
     deny x-middleware-subrequest;
     # ... rest of configuration
   }
   

Long-Term Recommendations

• Implement defense in depth (multi-layer authentication)
• Regular security audits
• Keep dependencies up to date
• Use a Web Application Firewall (WAF)

📚 Documentation

• Vulnerability Analysis
• Usage Guide
• Defense & Remediation

🧪 Testing

Manual Testing

# Run vulnerability test
python exploit/cve_2025_29927.py -u http://localhost:3000 -t

Automated Testing

# Run test suite
python tests/test_exploit.py

🔬 Research References

• NVD Entry
• Next.js Security Advisory
• Technical Analysis

📝 Changelog

v1.0.0 (2025-04-02)

• Initial release
• Single target exploitation
• Batch scanning support
• Docker vulnerable environment
• Comprehensive documentation

👥 Contributors

• [Your Name] - Initial implementation

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

⚠️ Legal Disclaimer

Important: This tool is intended for educational and authorized security testing purposes only.

• Only use on systems you own or have explicit permission to test
• Unauthorized access to computer systems is illegal
• Report vulnerabilities responsibly to vendors
• Follow responsible disclosure guidelines

By using this tool, you agree to:

• Comply with all applicable laws and regulations
• Use only for authorized security testing
• Report discovered vulnerabilities responsibly
• Not use for malicious purposes

📞 Reporting Vulnerabilities

If you find issues with this tool or discover new vulnerabilities, please report responsibly:

1. Contact the vendor (Vercel/Next.js team)
2. Follow responsible disclosure guidelines
3. Consider joining a bug bounty program

🙏 Acknowledgments

• Vercel/Next.js team for timely disclosure and fix
• Security research community for analysis and testing
• Vulnerability discoverer

Remember: Security research should always be ethical and legal. Use your skills to make the internet safer! 🛡️