This bug was fixed in the package initramfs-tools - 0.131ubuntu14
--------------- initramfs-tools (0.131ubuntu14) cosmic; urgency=medium
* hooks/framebuffer: manual_add_modules vboxvideo to support graphical boot in VirtualBox. LP: #1796822
-- Dimitri John Ledkov <email address hidden> Wed, 10 Oct 2018 11:06:00 +0100
This bug was fixed in the package initramfs-tools - 0.131ubuntu14
---------------
initramfs-tools (0.131ubuntu14) cosmic; urgency=medium
* hooks/framebuffer: manual_add_modules vboxvideo to support graphical
boot in VirtualBox. LP: #1796822
-- Dimitri John Ledkov <email address hidden> Wed, 10 Oct 2018 11:06:00 +0100