The RegistrationMagic WordPress plugin before 6.0.9.5 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.
https://wpscan.com/vulnerability/b8c75098-41a9-4b24-9f6b-c3144f230cd8/