The Contact Form 7 plugin for WordPress is vulnerable to Order Replay in all versions up to, and including, 6.0.5 via the wpcf7_stripe_skip_spam_check function due to insufficient validation on a user controlled key. This makes it possible for unauthenticated attackers to reuse a single Stripe PaymentIntent for multiple transactions. Only the first transaction is processed via Stripe, but the plugin sends a successful email message for each transaction, which may trick an administrator into fulfilling each order.
The product does not validate or incorrectly validates the integrity check values or “checksums” of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.