New krb5 packages are available for CentOS-3 x86_64. Refer to
https://rhn.redhat.com/errata/RHSA-2005-012.html.

RPMS/krb5-devel-1.2.7-38.x86_64.rpm
RPMS/krb5-libs-1.2.7-38.i386.rpm
RPMS/krb5-libs-1.2.7-38.x86_64.rpm
RPMS/krb5-server-1.2.7-38.x86_64.rpm
RPMS/krb5-workstation-1.2.7-38.x86_64.rpm
SRPMS/krb5-1.2.7-38.src.rpm

Execute "yum update krb5" to apply.