The RegistrationMagic WordPress plugin before 6.0.9.9 does not escape a registration form field value before outputting it in an HTML attribute on an administrative page, allowing unauthenticated users to perform Stored Cross-Site Scripting attacks against high privilege users such as admin.
https://wpscan.com/vulnerability/16661d09-6f8f-4f87-93b9-67a2f8b728f7/