The following errata for CentOS-2 have been built and uploaded to the centos mirror:

RHSA-2006:0179-01 Critical: auth_ldap security update

Files available:
auth_ldap-1.4.8-3.1.i386.rpm

More details are available from the RedHat web site at https://rhn.redhat.com/errata/rh21as-errata.html

The easy way to make sure you are up to date with all the latest patches is to run:
# yum update