Jexactyl: Stripe checkout confirmation accepts mismatched-currency/amount payments as full payment (payment forgery)

Jexactyl is a customisable game management panel and billing system. Prior to 4.0.5, the POST /api/client/billing/stripe/process endpoint accepts a client-supplied Stripe Checkout Session when payment_status is paid but does not compare amount_total or currency with the referenced order and configured billing currency. On an instance where the billing module is enabled and a Stripe secret key is configured, an authenticated client can therefore complete a lower-value or mismatched-currency payment and cause the order to be processed, provisioning, renewing, upgrading, or unsuspending the purchased server for less than the required price. This issue is fixed in version 4.0.5.