Marking the lightdm as invalid as it seems, from Nathan's description, that the issue is with light-locker.
** Changed in: lightdm (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1515662 Title: Major security issue with light-locker - console switching gives access to other screens for a few seconds Status in light-locker package in Ubuntu: New Status in lightdm package in Ubuntu: Invalid Bug description: light-locker is completely insecure for X configurations with multiple screens that are not using a single display. My setup - 4 monitors, nvidia, each with separate screen. If I lock screen and then control-alt-f7 back to X, only one single screen is protected. After several seconds, it forces a switch to the lock display, but in the mean time, the other three screens are COMPLETELY UNPROTECTED. It only takes a few seconds to launch a terminal and killall light- locker and I have unrestricted access to all. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/light-locker/+bug/1515662/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp