Segmentation fault (core dumped) after 16.04 upgrade

Question

I'm having this problem after i upgraded my kubuntu from 15.10 to 16.04. Actually everything works fine, the problem is that whenever i try to use the sudo command with a specific user, the Segmentation fault (core dumped) message appear.

If i try to cast a command without sudo, everything is fine. If i try to change user (su username) or login as root (su root) everything is fine.

So, this happens only when i'm logged with the user gmocciaro and i use the sudo command

I tried to:

• Change the /etc/sudoers permissions to 440
• Reinstall sudo
• remove and re-add the user as sudo (from root) adduser gmocciaro sudo

gmocciaro is the broken user

Little examples:

gmocciaro@epdev01:~$ sudo echo "Hi!"
Segmentation fault (core dumped)
gmocciaro@epdev01:~$ echo "Hi!"
Hi!


root@epdev01:/home/gmocciaro# sudo echo "Hi!"
Hi!
root@epdev01:/home/gmocciaro# echo "Hi!"
Hi!

cat /etc/sudoers

root@epdev01:/home/gmocciaro# cat /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults        env_reset
Defaults        mail_badpass
Defaults        secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root            ALL=(ALL:ALL) ALL
epdev           ALL=(ALL:ALL) ALL
gmocciaro       ALL=(ALL:ALL) ALL


# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL

# Allow members of group sudo to execute any command                                                                                                             
%sudo   ALL=(ALL:ALL) ALL                                                                                                                                        

# See sudoers(5) for more information on "#include" directives:                                                                                                  

#includedir /etc/sudoers.d

With a brand new user "dummy"

root@epdev01:/home/gmocciaro# sudo adduser dummy
Adding user `dummy' ...
Adding new group `dummy' (1001) ...
Adding new user `dummy' (1002) with group `dummy' ...
Creating home directory `/home/dummy' ...
Copying files from `/etc/skel' ...
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully

root@epdev01:/home/gmocciaro# adduser dummy sudo
Adding user `dummy' to group `sudo' ...
Adding user dummy to group sudo

root@epdev01:/home/gmocciaro# su dummy
dummy@epdev01:/home/gmocciaro$ sudo echo "Hi!"
[sudo] password for dummy: 
Hi!

Can you help me? thanks a lot.