Comment by akvadrako

Is this a risk out of the box?

    $ docker run -it -u guest alpine 
    / $ su
    su: must be suid to work properly
    / $ login
    login: must be suid to work properly
    / $ find / -perm /4000 -print
    find: /root: Permission denied
    find: /proc/tty/driver: Permission denied
    / $