I can't reproduce this on a clean 10.13.1 (17B48) system, either at the login window or an authentication dialog. Update: And even after attempting it, checkin

I can't reproduce this on a clean 10.13.1 (17B48) system, either at the login window or an authentication dialog. Update: And even after attempting it, checking Directory Utility the root user is still disabled. So I wonder if something 3rd party has enabled the root user and left it passwordless.