menus do not enforce any security, they do hide links if the user is not in an allowed view role but that is all they do.
the page itself enforces security if a user tries to access an url for a page that is protected by roles that user is not a member of.
I am not aware of any bugs in this functionality.
possibly with a proxy server if it does any caching it could return a page with an unfiltered menu that was cached by a user who has permission