First, why aren’t you doing a full ‘yum update’ to bring the whole system up to 6.4?
Also, are you updating these packages to get new features or bug/security fixes? CentOS tracks the updates in RHEL exactly and RHEL backports many security and bug fixes without changing the base package version numbers. You can see these with:
rpm -q –changelog package_name where the CVE numbers will be mentioned, if you are checking for some particular security issue.
If you need new features, you may have to go to newer versions found elsewhere, but be very careful about replacing any base packages in your system – it is almost always the wrong thing to do. You need to know more about Linux than the Red Hat engineers…