Statamic: Missing authorization on Control Panel endpoint allows disclosure of user existence

Statamic is a Laravel and Git powered content management system (CMS). Prior to 5.74.1 and 6.24.0, an authenticated Control Panel user could use an endpoint intended for the user creation wizard to determine if a given email address belonged to an existing user, without having permission to view users, though the endpoint only exposed user existence and not any other user data. This issue is fixed in versions 5.74.1 and 6.24.0.