You can log in as root on the latest version of MacOS by pressing enter on the login prompt a few times. Just type in root as the user and press enter..there you go no PW required.
Not sure what else to say; is this the stupidest massive security hole ever?
Reproing the bug is simple (at least until Apple fixes it): Type the login “root,” then move the cursor into the password field and hit enter several times. It also apparently works if you simply hit the “login” button several times rather than using the keyboard, though a few tries may be necessary.