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

- VMM: fixed a problem which could lead to a wrong guest behavior on AMD CPUs (tickets #14831 and #15186)
- GUI: don't try to synchronize the HID LEDs if the VM window is not active or if it's minimized (Windows / Mac OS X hosts only; bug #14302)
- GUI: prevent a crash during startup under rare conditions
- GUI: sub-menu option to disable the guest-OS type overlay in the application dock icon on Mac OS X
- GUI: position off-screen windows to be fully visible again on relaunch
- GUI: hide the VT-x/AMD-V checkbox if raw-mode is not supported (usually Mac OS X hosts; bug #15178)
- PC speaker passthrough: new experimental feature, available on Linux host only
- Audio: several fixes for Mac OS X hosts + guests
- Audio: properly handle default audio device changes (Windows hosts)
- USB: serveral fixes for the xHCI controller (e.g. for webcam passthrough)
- BIOS: fixed int15/AH=83/AL=00 function (4.2.0 regression)
- iPXE: enable the HTTP download protocol on non-Linux hosts (bug #13628)
- Shared folders: fixed a failure to load the saved state under certain circumstances (bug #6314)
- Guest Control: added support for (cached) Active Directory authentication in case the domain controller is not reachable (anymore)
- Serial ports: raised the number of serial ports per VM from 2 to 4 (bug #9109)
- Serial ports: fix for the TCP/IP backend (Windows hosts only; bug #15188)
- SDK: make the Python webservice API binding work again (5.0 regression)
- Seamless mode: fixed a crash under certain circumstances (bug #15106)
- Linux hosts: fixed the /sbin/rcvboxdrv script as well as the missing shebang in two scripts (bugs #15055 and #15057)
- Linux hosts: properly uninstall Python files installed by the .run installer
- Windows hosts: hardening fix required for recent Windows insider builds (bug #14052)
- Windows hosts: fixed Python installation path (bug #13131)
- Windows hosts: support MTU larger than 2 KB with bridged networking (bug #15140)
- Windows hosts / guests: properly sign binaries using a sha-256 certificate (bug #15054)
- Windows Additions: fixed guest property enumeration of logged-in users
- Windows Additions: fixed sporadical failure of the graphics driver in Windows 10 guests (bug #14409)
- Windows Additions: under rare circumstances no mouse movement events were delivered to the guest