Vulnerabilities in XFree86 packages may allow local or remote unauthorized users the ability to do the following:
1. xterm(1), provided as part of the XFree86 packages, provides an escape sequence for reporting the current window title. This escape sequence takes the current title and places it directly on the command line. An unauthorized local or remote user can create an escape sequence that sets the Xterm window title to an arbitrary command, and then reports it to the command line. Since it is not possible to embed a carriage return into the window title, the unauthorized user would then have to convince the user to press Enter for the shell to process the title as a command.
2. It is possible for a local or remote unauthorized user to lock up xterm(1) by sending an invalid "DEC UDK" escape sequence.
3. The xdm(1) display manager, with the "authComplain" set to false, allows unauthorized local or remote users to connect to the X server if the xdm(1) auth directory does not exist. (Reference the xdm manpages for the default values of authComplain and auth directory.)
4. A vulnerability in the "MIT-SHM" extension of the X server may allow local users to read and write shared memory.
5. The X server may set the "/dev/dri" directory permissions incorrectly. Since the "/dev/dri" is under the root filesystem and has world write permissions, local unprivileged users can create files in the root filesystem.
Please see the following CVE issues for more details: