VMware has issued a patch for a “severe” problem in ESXi 6.0.
How severe? Plenty severe: VMs might not backup or power on if you “upgrade to or install ESXi 6.0.x. Other symptoms include an inability to expand the size of a virtual disk or to take “virtual machine quiesced snapshots.”
To implement the patch you'll need to restart the host and the shut down or migrate VMs. Which means a fair bit of work, even once you get VMware vSphere Update Manager to do the heavy lifting.
VMware's keeping vAdmins quite busy of late. VSphere 6.0.0a debuted quietly a couple of weeks back. The company's security mailing list is also pumping out frequent updates about products impacted by the “SKIP” JRE mess, aka CVE-2014-6593. At the time of writing, several VMware products await their patch for that problem. ®