Can this be tested from the outside?

Partly. MLVibeScan checks webhook code, signature verification and idempotent fulfilment; source and deep checks require purchase, domain verification and explicit consent.

Is blocking access in the UI enough?

No. Security decisions must be enforced server-side for every request, regardless of the client an attacker uses.

When is the finding fixed?

Only when the control holds in a controlled re-test and no contradictory source/runtime observation remains.

Security guidance for vibe apps

Stripe webhooks require cryptographic verification

A success URL or client-provided status is not payment proof. Only a Stripe-signed webhook event may unlock a domain pass or fulfil a purchase.

Reviewed by René Matis · MATIS LABS · Updated 15 August 2026

The scan is free and takes about twenty seconds. You see straight away how many findings there are and how serious they are.

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How to recognise the problem

Without `constructEvent` on the untouched request body, a fabricated request may be treated as a genuine payment event.

A working happy path does not prove this boundary. Always test with a second user, while signed out or with an intentionally forbidden input.

How to fix it reliably

Verify signature and event ID before fulfilment, process retries idempotently and never trust client fields for amount or status.

The control belongs at the server-side trust boundary. A hidden button, different client copy or browser-only validation is not a security control.

Re-test instead of hoping

MLVibeScan checks webhook code, signature verification and idempotent fulfilment. A re-test compares the stable protection target with the previous result and reports fixed, partially fixed, unchanged or regression.

Automated checks cover recurring patterns. High-risk business logic may additionally require an individually scoped penetration test.

What we check automatically

webhook code, signature verification and idempotent fulfilment
Confidence and counter-checking
Stable fingerprints for re-tests

Frequently asked questions

Can this be tested from the outside?: Partly. MLVibeScan checks webhook code, signature verification and idempotent fulfilment; source and deep checks require purchase, domain verification and explicit consent.
Is blocking access in the UI enough?: No. Security decisions must be enforced server-side for every request, regardless of the client an attacker uses.
When is the finding fixed?: Only when the control holds in a controlled re-test and no contradictory source/runtime observation remains.