Updated GDM packages are available which correct a local crash if XDMCP is enabled.
GDM is the GNOME Display Manager for X. Two bugs have been found in the X Display Manager Control Protocol (XDMCP) which could allow a denial of service attack (DoS) by crashing the gdm daemon. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the names CAN-2003-0548 and CAN-2003-0549 to these issues. This attack is only possible if XDMCP is enabled. XDMCP is not enabled by default in CentOS Linux distributions. In addition is documented best practise that XDMCP should only ever be run on trusted networks. Users of XDMCP in GDM should upgrade to these erratum packages which contain backported security fixes are are not vulnerable to these issues. Note that CentOS Linux 2.1 is not vulnerable to CAN-2003-0547, a vulnerability that allows a local user to read any text file, as it did not have the "examine session errors" feature.