I hadn't experienced that issue until yesterday, but it happened to me 5 or 6 times since then. Always when pressing Ctrl+C while working in gnome-terminal. I'm in a default Ubuntu session (wayland).
osomon@bribon:~$ LANG=C apt policy gdm3 gnome-shell gnome-terminal console-setup gdm3: Installed: 3.25.90.1-0ubuntu4 Candidate: 3.26.0-1ubuntu1 Version table: 3.26.0-1ubuntu1 500 500 http://es.archive.ubuntu.com/ubuntu artful/main amd64 Packages *** 3.25.90.1-0ubuntu4 100 100 /var/lib/dpkg/status gnome-shell: Installed: 3.25.91-0ubuntu4 Candidate: 3.25.91-0ubuntu5 Version table: 3.25.91-0ubuntu5 500 500 http://es.archive.ubuntu.com/ubuntu artful/main amd64 Packages *** 3.25.91-0ubuntu4 100 100 /var/lib/dpkg/status gnome-terminal: Installed: 3.24.2-0ubuntu4 Candidate: 3.24.2-0ubuntu4 Version table: *** 3.24.2-0ubuntu4 500 500 http://es.archive.ubuntu.com/ubuntu artful/main amd64 Packages 100 /var/lib/dpkg/status console-setup: Installed: 1.166ubuntu4 Candidate: 1.166ubuntu4 Version table: *** 1.166ubuntu4 500 500 http://es.archive.ubuntu.com/ubuntu artful/main amd64 Packages 500 http://es.archive.ubuntu.com/ubuntu artful/main i386 Packages 100 /var/lib/dpkg/status -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/1710637 Title: Input falls through to gdm3 and terminates the session on Ctrl+C Status in console-setup package in Ubuntu: Fix Released Status in gdm3 package in Ubuntu: Incomplete Status in gnome-shell package in Ubuntu: Incomplete Status in mutter package in Ubuntu: Incomplete Bug description: Multiple times a day I find myself without a session after hitting Ctrl+C in a terminal, it seems the input falls through the Ubuntu/GNOME session and to gdm, which itself decides to terminate. Even worse, when this happens, you can briefly see your login password in plaintext in the virtual terminal. You can see the password however long you want if you stop the gdm service when this happens. I don't have a good way to reproduce, but it seems locking the session with a keyboard shortcut, subsequently unlocking it, maybe suspending, at some point brings this behaviour into the picture, until the session dies with a Ctrl+C. ProblemType: Bug DistroRelease: Ubuntu 17.10 Package: gdm3 3.24.2-1ubuntu9 ProcVersionSignature: Ubuntu 4.11.0-13.19-generic 4.11.12 Uname: Linux 4.11.0-13-generic x86_64 NonfreeKernelModules: zfs zunicode zavl zcommon znvpair ApportVersion: 2.20.6-0ubuntu5 Architecture: amd64 CurrentDesktop: GNOME Date: Mon Aug 14 15:54:34 2017 InstallationDate: Installed on 2016-05-06 (464 days ago) InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1) SourcePackage: gdm3 UpgradeStatus: Upgraded to artful on 2017-07-19 (25 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/console-setup/+bug/1710637/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp