Besides various GUI, E1000, storage, and VMM improvements, VirtualBox 5.1.12 adds a bunch of goodies for Linux users, among which we can mention initial support for the upcoming Linux 4.10 kernel, as well as better support for Linux kernel 4.9 for hosts. Additionally, there’s better support for the Linux 2.6.28 kernel series, which is no longer officially supported, for both Linux hosts and guests, and it looks like the Linux Additions component now warns users about a known bug with older Linux guests.