1. Ubuntu Security Notices
  2. USN-3285-1

USN-3285-1: LightDM vulnerability

Publication date

12 May 2017

Overview

LightDM could allow unintended access to files.

Releases

Packages

Details

Tyler Hicks discovered that LightDM did not confine the user session for guest
users. An attacker with physical access could use this issue to access files
and other resources that they should not be able to access. In the default
installation, this includes files in the home directories of other users on the
system. This update fixes the issue by disabling the guest session. It may be
re-enabled in a future update. Please see the bug referenced below for
instructions on how to manually re-enable the guest session.

Tyler Hicks discovered that LightDM did not confine the user session for guest
users. An attacker with physical access could use this issue to access files
and other resources that they should not be able to access. In the default
installation, this includes files in the home directories of other users on the
system. This update fixes the issue by disabling the guest session. It may be
re-enabled in a future update. Please see the bug referenced below for
instructions on how to manually re-enable the guest session.

Update instructions

After a standard system update you need to reboot your computer to make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
17.04 zesty lightdm –  1.22.0-0ubuntu2.1
16.10 yakkety lightdm –  1.19.5-0ubuntu1.2

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References

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