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

- GUI: fixed issue with opening '.vbox' files and it's aliases
- GUI: keyboard grabbing fixes (bugs #15771 and #15745)
- GUI: fix for passing through Ctrl + mouse-click (Mac OS X hosts only; bug #15714)
- GUI: fixed automatic deletion of extension pack files (bugs #11352 and #14742)
- USB: fixed showing unknown device instead of the manufacturer or product description under certain circumstances (5.1.0 regression; bug #15764)
- XHCI: another fix for a hanging guest under certain conditions as result of the fix for bug #15747, this time for Windows 7 guests
- Serial: fixed high CPU usage with certain USB to serial converters on Linux hosts (bug #7796)
- Storage: fixed attaching stream optimized VMDK images (bug #14764)
- Storage: reject image variants which are unsupported by the backend (bug #7227)
- Storage: fixed loading saved states created with VirtualBox 5.0.10 and older when using a SCSI controller (bug #15865)
- Storage: fixed broken NVMe emulation if the host I/O cache setting is enabled
- Storage: fixed using multiple NVMe controllers if ICH9 is used
- NVMe: fixed a crash during reset which could happen under certain circumstances
- Audio: fixed microphone input (5.1.2 regression; bugs #14386 and #15802)
- Audio: fixed crashes under certain conditions (5.1.0 regression; bug #15887 and others)
- Audio: fixed recording with the ALSA backend (5.1 regression)
- Audio: fixed stream access mode with OSS backend (5.1 regression, thanks to Jung-uk Kim)
- E1000: do also return masked bits when reading the ICR register, this fixes booting from iPXE (5.1.2 regression; bug #15846)
- BIOS: fixed 4bpp scanline calculation (bug #15787)
- API: relax the check for the version attribute in OVF/OVA appliances (bug #15856)
- Windows hosts: fixed crashes when terminating the VM selector or other VBox COM clients (bug #15726 and others)
- Linux Installer: fixed path to the documentation in .rpm packages (5.1.0 regression)
- Linux Installer: fixed the vboxdrv.sh script to prevent an SELinux complaint (bug #15816)
- Linux hosts: don't use 32-bit legacy capabilities
- Linux Additions: Linux 4.8 fix for the kernel display driver (bugs #15890 and #15896)
- Linux Additions: don't load the kernel modules provided by the Linux distribution but load the kernel modules from the official Guest Additions package instead (bug #15324)
- Linux Additions: fix dynamic resizing problems in recent Linux guests (bug #15875)
- User Manual: fixed error in the VBoxManage chapter for the getextradata enumerate example (bug #15862)