This is a maintenance release. The following items were fixed and/or added:
VMM: refined measurement of TSC frequency on the host, improves timekeeping for guests VMM: decreased CPU load resulting from guest MMIO writes to the virtual APIC VMM: fixed interception of debug exceptions, observed while using the dbx debugger on Solaris guests (VT-x only) GUI: 3D overlay window positioning code improved, fixed potential misplacement of 3D accelerated guest graphics content GUI: fixed accident SSL authentication failures during update check on Windows hosts (bug #12969) GUI: never send the "ACPI power" keyboard scancode to the guest, we have the ACPI power button for that GUI: was unable to properly restore seamless mode VM from snapshot/saved-state under some circumstances VBoxHeadless: don't crash if 3D is enabled in the VM settings (bug #10250) ATA: fixed several passthrough issues (bugs #12310, #1360) Audio: fixed DirectSound failure when the the host has no audio input device (Windows hosts only; bug #9205) SB16: fixed compatibility issue (bug #13769) Storage: fixed broken CD/DVD passthrough when using the IDE controller (bug #12310) NAT: new ping proxy for Windows hosts (bug #11871) NAT: Properly report outbound connect(2) failures to guest with TCP RST or ICMP (bug #10525) NAT Network: no need for frequent wakeups in VBoxNetDHCP and VBoxNetNAT (bug #11681) Host-only adapter: prevent Windows from creating an "Unidentified network" (bug #9688) Bridged Networking: don't leak host-to-guest traffic to the wireless network when bridging to a wireless interface (bug #13714) Main: fixed a possible race when changing the medium leading to a deadlock under rare conditions (bug #13722) VBoxManage: fixed return code if starting a VM failed (bug #13773) API: fixed 2 deadlock opportunities related to medium handling (bugs #13789, #13801, thank you Alexander Urakov) API: fixed bug in XPCOM which created too few worker threads, sporadically resulting in a deadlock (bug #13802, thank you Alexander Urakov) SDK: fixed a garbage collection leak in the Python VirtualBox webservice API binding (bug #13817) Linux hosts: fixes for activated SMAP (Broadwell and later, bug #13820) X11 guests: prevent unwanted hiding of guest screens on multi-monitor guests (bug #13287) X11 guests: added support for X.Org Server 1.17 X11 Additions: fixed a memory leak in VBoxService if libdbus is available but dbus-daemon isn't running (bug #13770) Windows Additions: prevent VBox WDDM driver from loading if host reports weak OpenGL capabilities. 3D content now can be shown over Remote Desktop connection. Windows Additions: some fixes for recent Windows 10 Previews Linux Additions: fixed a compatibility issue with 64-bit Linux 2.4 kernels Linux Additions: fixed a potential use-after-free when unloading the VBoxGuest module Linux Additions: Linux 3.19 fixes (bug #13741)