Recently when running vagrant on one of my existing virtual machines I received the following warning:

==> ServerUbuntu16: Vagrant has detected a configuration issue which exposes a
==> ServerUbuntu16: vulnerability with the installed version of VirtualBox. The
==> ServerUbuntu16: current guest is configured to use an E1000 NIC type for a
==> ServerUbuntu16: network adapter which is vulnerable in this version of VirtualBox.
==> ServerUbuntu16: Ensure the guest is trusted to use this configuration or update
==> ServerUbuntu16: the NIC type using one of the methods below:
==> ServerUbuntu16:
==> ServerUbuntu16: https://www.vagrantup.com/docs/virtualbox/configuration.html#default-nic-type
==> ServerUbuntu16: https://www.vagrantup.com/docs/virtualbox/networking.html#virtualbox-nic-type

After some digging around it turns out that this issue was fixed in VirtualBox version 5.2.2 but due to the way Oracle document their releases on a quarterly basis no mention was made of it.
There are two solutions to this issue then:

  1. Upgrade to virtualbox 5.2.2 or higher, this comes with the usual caveats of upgrading VirtualBox where all VMs need to be stopped and you need to be vigilant of contract changes in VirtualBox’s manager interface.
  2. Switch NIC type in the virtual machine
    1. Find list of nictype from the virtualbox manual under the modifyvm command
    2. As it currently stands they are Am79C970A|Am79C973|82540EM|82543GC|82545EM|virtio
    3. Set the nic type via vagrant: 
       config.vm.network "private_network", ip: "192.168.50.4",
   nic_type: "virtio"