Just a quick guide on how to download and install patches for VMware ESXi (free version).

Go to the VMware Patch Portal, select the product and version to view and download available patches:

https://www.vmware.com/patchmgr/findPatch.portal

In this example, I'm going from ESXi 5.5.0 build 1474528 to 5.5.0 build 1623387 (Update 1).

When the download is complete, upload the entire zip file to a datastore on your ESXi host.

Patches

SSH to your host.

Enter maintenance mode.

# vim-cmd hostsvc/maintenance_mode_enter

Verify the patch file.

# cd /vmfs/volumes/datastore1/Patches/
/vmfs/volumes/52ed3575-a67d75d2-17ab-001cc4d54e5f/Patches # ls
ESXi550-201312001.zip                 update-from-esxi5.5-5.5_update01.zip

Run the update.

# esxcli software vib update -d /vmfs/volumes/datastore1/Patches/update-from-esxi5.5-5.5_update01.zip

Verify.

# esxcli software vib list

Reboot.

# reboot

Exit maintenance mode.

# vim-cmd hostsvc/maintenance_mode_exit

Done.

ESXi Version