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

- GUI: mouse events did not reach host windows behind the transparent VM window (Mac OS X hosts only; bug #16246)
- Audio: fixed accidental crashes when using the AC'97 sound emulation (bug #16959)
- Audio: fixed crash when default input or output devices have changed (bugs #16968, #16969, #17004)
- Audio: fixed recording when using the ALSA backend
- Audio: fixed handle leak when using the OSS backend
- E1000: fixed a crash related to VLAN traffic over internal network (5.1.26 regression; bug #16960)
- NAT: apply --natbindip1 to TCP connections (bug #16478)
- OVF: when importing an appliance with XHCI controller, don't add an OHCI controller.
- Mac OS X hosts: fixed a GUI crash if Spotlight is used from file dialogs (5.1.20 regression; bugs #16935, #16953)
- Linux hosts: fixed creating fixed sized VDI images (bug #17010)
- Linux hosts / guests: fixes for Linux 4.4 of openSUSE Leap 42.3 (bug #16966)
- Bridged networking: align outgoing packet at word boundary, preventing Windows host crash in MsLbfoProvider.
- Linux Additions: kernel drm driver support for custom EL7 Linux 3.10 kernel
- Solaris Additions: hide an informational message on the bootup console