On my 18.04, if I lock my session, when exit the screensaver, in particular conditions, my session is no longer locked and it is accessible without typing password. In terms of security, it's ugly. The lock-screen works fine, because if I lock my session, the password is required before the screensaver appears. As soon as the screensaver activates, then when exit screensaver, no more lock-screen. My display is a TV plugged in HDMI that I switch off after enabled lock-screen. Sometimes, the lock-screen is retained when exit screensaver. Could you help me to keep the lock-screen when exit the screensaver? I don't want to enable the lock-screen systematically when exit the screensaver, only if I enabled the lock-screen manually. Thank you in advance Edit: In my opinion, it's a critical security bug, because I can easily reproduce the problem. It seems to appears only with HDMI TV with the below conditions.


Steps to reproduce the issue :

  • Enable the locks-creen
  • Check it's locked
  • Press Escape to blank the screen
  • Switch off the TV HDMI
  • Wait 10 s
  • Press Ctrl to wake-up the lock-screen
  • Switch on the TV
  • The lock-screen is done!
  • After, no way to enable the lock-screen immediatly


$ apt-cache policy xscreensaver mate-screensaver gdm
  Installé : (aucun)
  Candidat : 5.36-1ubuntu1
 Table de version :
     5.36-1ubuntu1 500
        500 http://fr.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
  Installé : 1.20.0-1
  Candidat : 1.20.0-1
 Table de version :
 *** 1.20.0-1 500
        500 http://fr.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
        100 /var/lib/dpkg/status
  Installé : (aucun)
  Candidat : (aucun)
 Table de version :
  • It seems that you have two lock screens. Please add output of apt-cache policy xscreensaver mate-screensaver gdm to the question. – N0rbert Dec 31 '18 at 17:12
  • @N0rbert: done. One screensaver it seems. – NicolasSmith Jan 1 at 10:07
  • I can't reproduce your issue on clean Ubuntu MATE 18.04 LTS installation. Please provide more details - package names, method of MATE installation, screencast and so on. – N0rbert Jan 1 at 10:22
  • Crossposted on Mate forum: ubuntu-mate.community/t/… – NicolasSmith Jan 1 at 18:51

Your Answer

By clicking "Post Your Answer", you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.