I would recommend examining your PAM configuration files in /etc/pam.d/, especially the common-* files. You may want to try reinstalling pam to see if it warns you about changed configuration files too:
sudo apt-get --reinstall install libpam-runtime The stock versions of these files are in /usr/share/pam/common-* ** Changed in: gdm (Ubuntu) Status: New => Incomplete -- user is able to login without password https://bugs.launchpad.net/bugs/212923 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs