Microsoft released this Offline Virtual Machine Servicing Tool 2.1 that allows you to perform operating system updates to your offline virtual machines that are stored in your Microsoft System Center Virtual Manager library.
This is helpful in keeping your offline virtual machines up-to-date so that when you create a new virtual machines from your selected library, you can confidently bring it online as it will not introduce vulnerables into your organization.
It also saved your time and effort in recreating library images when new service packs and updates are released.
Download it here. Click.