Bug confirmed for me too with Virtualbox 5.2.22 used on Mac OSX 10.14.3 with Ubuntu Desktop 16.04.6. I rolled kernel back to 4.4.0-142 and forced a vbox extensions rebuild (https://askubuntu.com/a/1127079/1698) and was operational again but only temporarily because I'm forced to remain on the old kernel until this bug is fixed.
Bug confirmed for me too with Virtualbox 5.2.22 used on Mac OSX 10.14.3 with Ubuntu Desktop 16.04.6. I rolled kernel back to 4.4.0-142 and forced a vbox extensions rebuild (https:/ /askubuntu. com/a/1127079/ 1698) and was operational again but only temporarily because I'm forced to remain on the old kernel until this bug is fixed.