Tailgating would be the MOST likely attack used to bypass an access control vestibule. An access control vestibule is a physical security measure that requires individuals to go through a controlled space to access a secured area. Tailgating refers to the act of following closely behind someone who has been granted access to the controlled space, in an attempt to gain entry without proper authorization. Tailgating can be done intentionally or unintentionally, but in either case, it allows an unauthorized individual to gain access to the secured area.