Just checked on my cheese grater Mac Pro running 10.13.2 beta 5 public (updated yesterday) and was able to login from the opening screen after booting using root and blank password!!!! I used to only have my icon to click for login but there was also one for 'other' which I used to enter root.
No sign of the security update in the App Store
and can't seem to get rid of the 'other' login icon. (It doesn't show on my MacBook running beta 4 public)
My computer is wide open - need to keep my office locked
Is this Karma for me trying out a Surface Studio in a store earlier today? (nice machine but prices similar to top end iMac or the forthcoming iMacPro)
ps I was able to go to the user documents folder for my legitimate login and read the files so I did have root privileges.