[Pkg-xfce-devel] Bug#887773: It is possible to circumvent authentication after locking screen in lightdm

Josef Moosbauer josef at moosbauer.net
Fri Jan 19 20:21:36 UTC 2018

Package: lightdm
Version: 1.18.3-1

Debian 9.3 - last dist-upgrade today 1-19-2018
uname -a: Linux smo-zen 4.9.0-5-amd64 #1 SMP Debian 4.9.65-3+deb9u2
(2018-01-04) x86_64 GNU/Linux

When I should have to enter user/password to authenticate to continue
working after locking the screen using "dm-tool lock", I am able to
avoid that by swichtching to a non X console (ALT+F1) and back to X
(ALT+F7) and I am able to continue working without giving user/password

1. lock screen with "dm-tool lock"
2. wake up by moving mouse or pressing any key - authentication pops up
3. press ALT+F1
4. press ALT+F7
5. you are now back to work in the authenticated X-Session (Strange not
e: "dm-tool lock" does no longer lock the screen ie. does nothing)

I suggest step 4 to ask for user/password before giving access to the

kind regards Josef

kind regards / mit freundlichen Grüßen

Moosbauer Josef

<josef at moosbauer.net>

GPG Fingerprint 6748 9413 0EF1 5B23 D707  DBFA 570B 00E3 4689 8CC9

"Of course I'm crazy, but that doesn't mean I'm wrong. I'm mad but not


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