Admidio 5.0.0 before 5.0.15 Unauthenticated Stored XSS via Registration Name

Admidio 5.0.0 before 5.0.15 contains an unauthenticated stored cross-site scripting vulnerability in RegistrationPresenter.php, which inserts the raw FIRST_NAME registration value into an unencoded data-message attribute. Attackers can register with a double-quoted event handler that executes JavaScript in an administrator's session when they hover the entry on the Manage registrations page.