CVE-2011-4029
The LockServer function in os/utils.c in X.Org xserver before 1.11.2 allows local users to change the permissions of arbitrary files to 444, read those files, and possibly cause a denial of service (removed execution permission) via a symlink attack on a temporary lock file.
Date published : 2012-07-03
http://cgit.freedesktop.org/xorg/xserver/commit/?id=b67581cf825940fdf52bf2e0af4330e695d724a4
http://lists.freedesktop.org/archives/xorg/2011-October/053680.html