The following errata for CentOS-2 have been built and uploaded the the centos mirror:
RHSA-2005:150-01 Important: postgresql security update
Files available: postgresql-7.1.3-6.rhel2.1AS.i386.rpm postgresql-contrib-7.1.3-6.rhel2.1AS.i386.rpm postgresql-devel-7.1.3-6.rhel2.1AS.i386.rpm postgresql-docs-7.1.3-6.rhel2.1AS.i386.rpm postgresql-jdbc-7.1.3-6.rhel2.1AS.i386.rpm postgresql-libs-7.1.3-6.rhel2.1AS.i386.rpm postgresql-odbc-7.1.3-6.rhel2.1AS.i386.rpm postgresql-perl-7.1.3-6.rhel2.1AS.i386.rpm postgresql-python-7.1.3-6.rhel2.1AS.i386.rpm postgresql-server-7.1.3-6.rhel2.1AS.i386.rpm postgresql-tcl-7.1.3-6.rhel2.1AS.i386.rpm postgresql-test-7.1.3-6.rhel2.1AS.i386.rpm postgresql-tk-7.1.3-6.rhel2.1AS.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