Security Guide
Payment Processing

Security for Payment Processing

Payment integration is where security failures have the most direct financial impact. Incorrect Stripe integration, missing webhook verification, and client-side price trust are the most common issues in vibe-coded apps.

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Why Security Matters for Payment Processing

Payment vulnerabilities result in direct financial loss. Price manipulation, fake payment confirmations, and refund abuse are all common in AI-generated payment code. Stripe provides excellent security primitives, but the integration code must use them correctly. Most AI tools generate Stripe integrations that trust client-submitted prices, don't verify webhook signatures, and expose payment-related API endpoints without proper authorization.

Security Risks

Client-side price manipulation

critical

Payment amounts sent from the frontend and trusted by the server without validation.

Mitigation

Always calculate prices server-side from your product database. Create Stripe Payment Intents with server-calculated amounts only.

Unverified webhooks

critical

Processing Stripe webhook events without signature verification, allowing fake payment confirmations.

Mitigation

Always verify Stripe webhook signatures using your webhook signing secret. Reject any event with an invalid signature.

Refund endpoint abuse

high

Refund API endpoints without proper authorization allowing unauthorized refunds.

Mitigation

Restrict refund operations to admin users with additional authentication. Implement refund limits and approval workflows.

Security Checklist

Server-side price calculationMust Have

All payment amounts calculated from your product database on the server.

Stripe webhook signature verificationMust Have

Verify every webhook event signature before processing.

Use Stripe Checkout or Payment IntentsMust Have

Use Stripe's recommended payment flows. Never handle raw card numbers.

Idempotent payment processingShould Have

Use idempotency keys to prevent duplicate charges from retries.

Refund authorizationShould Have

Only authorized admin users can initiate refunds, with amount limits.

Payment event loggingShould Have

Log all payment events for reconciliation and dispute resolution.

Real-World Scenario

A developer builds a course platform using Bolt with Stripe. The checkout page sends the course price to the server to create a Stripe Checkout Session. An attacker intercepts the request and changes the price from $299 to $1. The server creates a Checkout Session for $1, the attacker pays, and receives full access to the $299 course.

Frequently Asked Questions

How do I secure Stripe webhook endpoints?

Use stripe.webhooks.constructEvent() with your webhook signing secret to verify the signature. Return 400 for invalid signatures. Store the signing secret in environment variables, never in code.

Is it safe to use Stripe.js on the frontend?

Yes, Stripe.js is designed for frontend use. It tokenizes card data so your server never sees card numbers. The security risk is in how you use the server-side Stripe API, not Stripe.js itself.

Should I store payment data in my database?

Store only Stripe customer IDs, subscription IDs, and payment intent IDs. Never store card numbers, CVVs, or full payment tokens. Let Stripe handle payment data storage — that's how you stay PCI compliant.

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