VMs with NAT fail on OS X 10.11.6

[EdwardC]

The issue appears to have been introduced in VirtualBox 5.0.26. Version 5.0.24 does not exhibit the same fault. I've reproduced it on a second machine running OS X 10.11.6, but could not reproduce it on a machine running OS X 10.11.5.

I'm running VirtualBox 5.1.2 on OS X 10.11.6 and any VM with a network adapter attached to "NAT" will fail with the following error:

The VM session was aborted.

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: SessionMachine
Interface: ISession {7844aa05-b02e-4cdd-a04f-ade4a762e6b7}

Running VBoxHeadless from the command-line produces the following output:

Oracle VM VirtualBox Headless Interface 5.1.2
(C) 2008-2016 Oracle Corporation
All rights reserved.

Segmentation fault: 11

Switching the attachment to "NAT Network" allows the VM to boot normally. The same issue occurs across a number of Windows and Linux guests which used to function without issue. When the VMs were last functioning correctly I was using an earlier version of OS X, and VirtualBox 5.0, though I don't recall the exact versions. Downgrading to VirtualBox 5.0.26 does not allow the VMs to boot.