You can easily upgrade to newest CentOS version if you are use a dedicated server or Xen VPS,KVM VPS,HVM VPS. But you can not upgrade if your VPS is based on OpenVz How upgrade CentOS 6.3 to 6.4/6.5/6.6 or from CentOS 5.x to 5.9?  Make sure your server is a dedicated server or Xen VPS,KVM VPS,HVM VPS Backup data  SSH login via root and run command "yum -y upgrade" Wait 10-60 minutes, done! Check CentOS version by command "cat /etc/redhat-release" NOTE: You can not upgrade from CentOS 5.x to 6.x We recommand you upgrade ASAP after reload OS if you want try new version...