Update: You may want to have a look at my new blog post on this topic
as I am getting quite a few tickets regarding Spectre and Meltdown on vSphere Products and I just want to point you all to the official communication.
First of all, there are the Security Advisories for vSphere and Photon:
Then there is a good meta post on the official VMware Security Blog:
And last but not least there are two KB Articles containing some more Information on this Topic:
- VMware Response to Speculative Execution security issues, CVE-2017-5753, CVE-2017-5715, CVE-2017-5754 (aka Spectre and Meltdown)
- VMware Virtual Appliances and CVE-2017-5753, CVE-2017-5715 (Spectre), CVE-2017-5754 (Meltdown)