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

RHSA-2005:114-01 Low: imap security update

Files available:
imap-2001a-11.0as.i386.rpm
imap-devel-2001a-11.0as.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