So VMware released a security advisory (VMSA-2019-0009) about vulnerable VMware Tools.
In short it is recommended to upgrade all VMware Tools to at least version 10.3.10 (Build 10346) which is the newest at the time of writing.
After patching ESXi to the latest build, you might realize that the VMware tools you are left with, after upgrading the tools, in a VM, is 10.3.5 (build 10341)
One way to get the newest tools is to place the newest tools on your datastore.
Basically you just create a folder on your datastore /vmfs/volumes/<shared datastore>/SharedToolsDir
Download the 10.3.10 tools from VMware. https://my.vmware.com/web/vmware/details?downloadGroup=VMTOOLS10310&productId=491
Get the zip file with Windows and Linux tools. Unpack them, and copy the floppies and vmtools folders to the new datastore folder you created.
Afterwards you need to tell each ESXi hosts where to find the new tools. You do this by settings a advanced setting on each ESXi host.
You need to set UserVars.ProductLockerLocation to /vmfs/volumes/<shared datastore>/SharedToolsDir/
You need to reboot your hosts for it to detect the new tools right away.
Update: VMware ESXi 6.5 update 3 now contains VMware Tools 10.3.10, so there is not need for this fix in that version. Just update your vCenter and hosts.