The default configuration of XFCE 3.5.1 bypasses the Xauthority access control mechanism with an "xhost + localhost" command in the xinitrc program, which allows local users to sniff X Windows traffic and gain privileges.
libICE in XFree86 allows remote attackers to cause a denial of service by specifying a large value which is not properly checked by the SKIP_STRING macro.
XFree86 startx command is vulnerable to a symlink attack, allowing local users to create files in restricted directories, possibly allowing them to gain privileges or cause a denial of service.