Next.js Middleware Bypass (CVE-2025-29927) Proof of Concept This repository contains a proof of concept (POC) for CVE-2025-29927, a critical vulnerability in Next.js that allows attackers to bypass authorization checks implemented in middleware. 📋 Table of Contents Running the POC Application Using the Exploit Script How to Fix the Vulnerability Vulnerability Details Running the POC Application This Next.js application demonstrates the vulnerability with a protected dashboard route. Setup Instructions Clone the repository Install and run: bash npm install npm run build npm run start Access https://localhost:3000 in your browser Try accessing the protected dashboard at /dashboard Using the Exploit Script The exploit script can test any Next.js application for this vulnerability. Usage bash npm run exploit <target-url> Example bash npm run exploit https://localhost:3000/dashboard How it Works The exploit tool: 1. Takes a target URL as input 2. Makes a normal request to check if the route is protected 3. Attempts to bypass middleware using the x-middleware-subrequest header 4. Compares responses to determine vulnerability Sample Output “`bash === Next.js CVE-2025-29927 Middleware Bypass Tester === Target: https://localhost:3000/dashboard Testing vulnerability… Normal request status: 307 Bypass request status: 200 ⚠️ VULNERABLE The route is protected but accessible with the bypass header “` How to Fix the Vulnerability A fix implementation is available…Read More