USN-1099-1: GDM vulnerability

30 March 2011

gdm vulnerability

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

  • Ubuntu 10.10
  • Ubuntu 10.04 LTS
  • Ubuntu 9.10


A GDM vulnerability allows local attackers to gain root privileges.

Software Description

  • gdm - GNOME Display Manager


Sebastian Krahmer discovered that GDM (GNOME Display Manager) did not properly drop privileges when handling the cache directories used to store users’ dmrc and face icon files. This could allow a local attacker to change the ownership of arbitrary files, thereby gaining root privileges.

Update instructions

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

Ubuntu 10.10
gdm - 2.30.5-0ubuntu4.1
Ubuntu 10.04 LTS
gdm -
Ubuntu 9.10
gdm - 2.28.1-0ubuntu2.3

To update your system, please follow these instructions:

After a standard system update you need to log out all desktop sessions and restart GDM to make all the necessary changes.