You can check the version you have installed using:
esxcli system version get
The output of this command is something like this:
To upgrade your install:
esxcli software vib update -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml
It will take a while. When done, reboot and verify the upgrade.
You might also want to check out this vmware patch tracker site.