The Custom Fields Account Registration For Woocommerce WordPress plugin before 1.4 does not prevent its custom registration fields from writing to the user capabilities meta key on sites that use a non-default database table prefix, so an unauthenticated user who registers an account can be granted the administrator role when a correspondingly named field has been configured.
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.