This is a maintenance release. The following items were fixed and/or added:

- VMM: mask the VME CPUID capability on AMD Ryzen processors for now to make certain guests works, for example Windows XP
- VMM: emulate more SSE2 instructions
- VMM: properly clear the TF and AC flags when dispatching real-mode interrupts
- GUI: fixes to make the mini-toolbar work with recent versions of KDE / Plasma (bug #16325)
- GUI: fixed a potential crash when a VM with multiple screens is running in full screen / seamless mode and a host screen is removed, for example when connecting to the host via RDP
- GUI: fixed initial size hints for guests which set intermediate sizes before responding (bug #16593)
- GUI: prevent stopped screen updates or black screen on reboot in a multi-screen setup under certain conditions
- Audio: many improvements for Windows 10 guests (bugs #15189, #15925, #16170, #16682, #16794 and others)
- Storage: fixed possible crash when using Intels SPDK
- API: use the correct file name of the VM machine state if the VM settings directory is renamed, for example during grouping / ungrouping a VM (bugs #16075 and #16745)
- API: return the correct error code if powering up a VM fails
- API: video recording did not automatically start at VM start when enabled in the VM settings (bug #16803)
- API: when relocating a medium, check that the target path is fully qualified
- EFI: fix for VMs with more than 3504MB RAM (bug #11103)
- Host-only adapter: correctly determine IPv4 netmasks on Windows hosts (bug #16826)
- NAT network: properly do the refcounting for starting / stopping the NAT / DHCP services if the NAT network is changed while the adapter network connection type is anything else but NAT network
- VBoxManage: fixed controlvm videocapfile (bug #16779)
- Windows hosts: fixed crashes if driver verifier is enabled (bug #15741)
- Linux / Mac OS X hosts: more fixes for loading shared libraries (5.1.20 regression; bugs #16778, #16693)
- Linux hosts / guests: Linux 4.12 fixes (bugs #16725, #16800)
- Linux hosts / guests: reduce the kernel stack consumption for Linux kernels with CONFIG_CPUMASK_OFFSTACK defined
- Linux hosts / guests: fixes for kernel modules built with gcc-7 (bug #16772)
- Linux hosts / guests: Linux 4.13 fix (bug #16887)
- Linux hosts: don't depend on net-tools on newer distributions as this package is deprecated in favour of iproute (bug #16764)
- Linux hosts: make 2D video acceleration available for older Linux distributions (5.1 regression; bug #16858)
- Linux Additions: fix for dynamic resizing with Oracle Linux 6 with UEK4
- Linux Additions: make Fedora 25 and 26 Alpha work when 3D pass-through is enabled
- Linux Additions: no longer recommend removing distribution- installed Additions if they are updated to our guidelines