CVE-2011-4028
The LockServer function in os/utils.c in X.Org xserver before 1.11.2 allows local users to determine the existence of arbitrary files via a symlink attack on a temporary lock file, which is handled differently if the file exists.
Date published : 2012-07-03
http://cgit.freedesktop.org/xorg/xserver/commit/?id=6ba44b91e37622ef8c146d8f2ac92d708a18ed34
http://lists.freedesktop.org/archives/xorg/2011-October/053680.html