Securing the hypervisor platform is critical for building a secure virtualization infrastructure. VMware has made substantial progress in reducing the threat surface of the ESX hypervisor. Beginning with Version 4.0, the traditional ESX hypervisor was joined by the ESXi version of the hypervisor. The ESX version of the hypervisor had a larger footprint and a greater threat profile. ESXi versus ESX is similar to Windows Server Core versus the full version of Windows Server.

Starting with vSphere 5.0, the ESXi hypervisor replaced the ESX hypervisor; as a result, the console's interface was changed to a more streamlined and simple Graphical User Interface (GUI). In fact, the ESXi hypervisor is often run from a memory card instead of a dedicated hard drive due to its size.