PAY-006high SeverityPayment Processing & Webhook Integrity
Raw Request Body Preserved for Webhook Handler in Next.js
In Next.js App Router, agents use req.json() on webhook routes which breaks Stripe signature cryptographic checks.
1-Click Fix Prompt for Cursor & Claude Code
Review my codebase for "Raw Request Body Preserved for Webhook Handler in Next.js" (PAY-006). Issue: In Next.js App Router, agents use req.json() on webhook routes which breaks Stripe signature cryptographic checks. Remediation required: Read raw request buffer using await req.text() so the cryptographic signature matches the exact raw payload. Please: 1. Locate any occurrences of this issue across my repository. 2. Refactor the code to follow production standards without breaking existing functionality. 3. Provide a clear command or step to test and verify the fix.
Why AI Assistants Write This Bug
In Next.js App Router, agents use req.json() on webhook routes which breaks Stripe signature cryptographic checks.
AI code generation prioritizes immediate syntax execution over production edge cases. When an assistant hits an undefined variable or strict type error, it frequently takes the path of least resistance rather than implementing standard pre-launch security patterns.
Code Comparison
Common AI Code PatternVulnerable
// Vulnerable AI-generated pattern for: Raw Request Body Preserved for Webhook Handler in Next.js
// Flawed Stripe webhook handler
export async function POST(req: Request) {
const body = await req.json(); // BUG: Fails signature verification!
const signature = req.headers.get("stripe-signature");
// Unhandled events drop silently
return Response.json({ received: true });
}Launch-Ready Fix
// Production-ready fix for: Raw Request Body Preserved for Webhook Handler in Next.js
// Fixed Stripe webhook with raw text buffer
export async function POST(req: Request) {
const body = await req.text(); // Raw text preserves HMAC signature
const signature = req.headers.get("stripe-signature");
const event = stripe.webhooks.constructEvent(body, signature!, process.env.STRIPE_WEBHOOK_SECRET!);
// Acknowledge receipt with 200
return Response.json({ received: true }, { status: 200 });
}Remediation & Verification Checklist
Remediation: Read raw request buffer using await req.text() so the cryptographic signature matches the exact raw payload.
- Search your codebase for pattern matching "Raw Request Body Preserved for Webhook Handler in Next.js".
- Apply the recommended remediation: Read raw request buffer using await req.text() so the cryptographic signature matches the exact raw payload.
- Run local build and test commands to ensure no regressions.
- Verify in your browser or with curl that the issue is resolved.
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