[tempay]

It is disabled by default[1] (meaning you can't login as it), this vulnerability appears to enable the root user without setting a password. If the root user has already been enabled it doesn't work.

Anyone who does this should probably set a password for now and then disable the root user account once it has been patched.

[1] https://support.apple.com/en-us/HT204012

[srathi]

This is the best workaround for now. Enable the root user with a strong password till the bug is fixed by Apple.