Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux

B.25. gdm

Updated gdm packages that fix one security issue are now available for Red Hat Enterprise Linux 6.
The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) associated with each description below.
The GNOME Display Manager (GDM) provides the graphical login screen, shown shortly after boot up, log out, and when user-switching.
A race condition flaw was found in the way GDM handled the cache directories used to store users' dmrc and face icon files. A local attacker could use this flaw to trick GDM into changing the ownership of an arbitrary file via a symbolic link attack, allowing them to escalate their privileges.
Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for reporting this issue.
All users should upgrade to these updated packages, which contain a backported patch to correct this issue. GDM must be restarted for this update to take effect. Rebooting achieves this, but changing the runlevel from 5 to 3 and back to 5 also restarts GDM.