X.Org is an open source implementation of the X Window System. It provides the basic low-level functionality that full-fledged graphical user interfaces are designed upon. These xorg-x11 packages also provide the X.Org libXfont runtime library. A buffer overflow flaw was found in the way the libXfont library, used by the X.Org server, handled malformed font files compressed using UNIX compress. A malicious, local user could exploit this issue to potentially execute arbitrary code with the privileges of the X.Org server. Users of xorg-x11 should upgrade to these updated packages, which contain a backported patch to resolve this issue. All running X.Org server instances must be restarted for the update to take effect.