So there is a simple way for you to gain root access to a Mac with the latest operating system. It seems very simple, luckily I have not upgraded to that yet, so I can't test this our also.
They are working on a fix currently and I am sure it will be out shortly. The researcher who found the bug, Turkish developer Lemi Ergin seems to be coming under criticism as he seemed to of released this publicly without informing Apple first which is normally how these are done, and you can get paid for disclosing bugs normally.
Unitl an official patch is released you can use this workaround, published by Apple.
“Setting a root password prevents unauthorized access to your Mac,” the company explained.
"To enable the Root User and set a password, please follow the instructions here: https://support.apple.com/en-us/HT204012.
I am always interested in your thoughts so if you have any comments or feedback then please feel free to add any comments, or you can mail me here.