RegistrationMagic < 6.0.9.5 - Unauthenticated Payment Bypass via Amount-Blind PayPal Verification

Description

The plugin does not compare the verified PayPal capture's amount, currency, payee, or prior use against the registration it is finalising: its server-side check only confirms the capture status is COMPLETED. An unauthenticated attacker can therefore finalise an expensive paid registration with any genuinely-completed low-value capture, and replay a single capture across unlimited registrations because captures are not de-duplicated.