The root password is a copy of my old user password

[Chris Rodgers]

I did a fresh install of Linux Mint 18 "Sarah" and created a single user named "jack" with PASSWORD1 as the password. Later, I changed the password (using the "Users and Groups" graphical dialog) to PASSWORD2. Both logging in and using sudo now require PASSWORD2, as expected.

However, PASSWORD1 is still the password for the account root. I can tell because "su -" and "su - root" reject PASSWORD2 but accept PASSWORD1.

I would have expected that the root account was disabled until I explicitly set a password for it, not that it would silently copy my user password. If I knew my password was compromised and changed it, I wouldn't have thought to check that the root account was still using the compromised password.

In fact, I thought the root account was disabled on Linux Mint by default. See this question for instance: https://superuser.com/questions/323317/why-does-linux-ubuntu-mint-lack-a-root-account