ok I admit I am aware but woefully uninformed on Spectre & Meltdown and offer these for insight - maintenance and support is a bear and of course ignorance is no excuse
Here is a script to run a check
Ubuntu 17.10
https://linuxhint.com/check-patch-spectre-meltdown-ubuntu/
VirtualBox
https://forums.virtualbox.org/viewtopic.php?f=1&t=86118