CentOS Errata and Security Advisory 2007:0777
https://rhn.redhat.com/errata/RHSA-2007-0777.html
The following updated files have been uploaded and are currently syncing to the mirrors:
i386: gdm-2.16.0-31.0.1.el5.centos.i386.rpm
src: gdm-2.16.0-31.0.1.el5.centos.src.rpm