The following errata for CentOS-2 have been built and uploaded to the centos mirror:
RHSA-2005:843-01 Moderate: netpbm security update
Files available: netpbm-9.24-9.AS21.6.i386.rpm netpbm-devel-9.24-9.AS21.6.i386.rpm netpbm-progs-9.24-9.AS21.6.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