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

RHSA-2008:0886-01 Important: libxml2 security update

Files available:
libxml2-2.4.19-11.ent.i386.rpm
libxml2-devel-2.4.19-11.ent.i386.rpm
libxml2-python-2.4.19-11.ent.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