It's posted at LWN.net: "Problem Description:
A problem exists in the /etc/X11/Xsession file which disables the
Xauthority mechanism of the localhost. This means that anyone logged
into the localhost can arbitrarily connect to an X server running on
the localhost. This is only a problem with systems that allow remote
logins and is not a problem on systems that do not support remote
logins or multiple users."