CRTL+ALT+F7 bypasses the lock-screen with lightdm

[Ted]

This problem concerns every versions of Ubuntu 18 (Desktop or LTS) :

When I lock my session with the padlock icon, I can open it with CRTL+ALT+F7 without password.

This is the step to reproduce the problem:

- Install Ubuntu 18 (Desktop or LTS) with the default option.
The default windows manager is gnome

- Install lightdm => the opening window logging will be replaced by the opening window logging of lightdm

- Open a session

- Lock the session with the padlock icon (in the right upper corner, click on the down arrow and click on the padlock icon)

- The session seems lock because you can see the opening window logging wich asks you the password but press on CRTL+ALT+F7 and you can open the session without password.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: lightdm 1.28.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.18.0-10.11-generic 4.18.12
Uname: Linux 4.18.0-10-generic x86_64
ApportVersion: 2.20.10-0ubuntu13
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 15 15:26:04 2019
InstallationDate: Installed on 2019-04-11 (4 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)