USN-293-1: gdm vulnerability

9 June 2006

gdm vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 6.06 LTS
  • Ubuntu 5.10

Software Description

Details

If the admin configured a gdm theme that provided an user list, any user could activate the gdm setup program by first choosing the setup option from the menu, clicking on the user list and entering his own (instead of root’s) password. This allowed normal users to configure potentially dangerous features like remote or automatic login.

Please note that this does not affect a default Ubuntu installation, since the default theme does not provide an user list. In Ubuntu 6.06 you additionally have to have the “ConfigAvailable” setting enabled in gdm.conf to be vulnerable (it is disabled by default).

Ubuntu 5.04 is not affected by this flaw.

Update instructions

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

Ubuntu 6.06 LTS
gdm - 2.14.6-0ubuntu2.1
Ubuntu 5.10
gdm - 2.8.0.5-0ubuntu1.2

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

In general, a standard system upgrade is sufficient to effect the necessary changes.

References