This is a maintenance release. The following items were fixed and/or added:
VMM: fix for a bug in the Local APIC emulation causing a BSOD when booting certain guests (4.3.0 regression; bug #12240)
VMM: fixed loading of saved states if VT-x/AMD-V was disabled (4.3.2 regression; bug #12291)
VMM: fixed single-stepping inside the guest for certain instructions (VT-x only; bug #10947)
VMM: fixed a performance issue involving APIC accesses after rebooting a VM (4.3.0 regression; VT-x only; bug #12296)
VMM: fixed TPR patching to be enabled for 32-bit guests even when the chosen guest type is 64-bit (4.3.0 regression; AMD-V only)
VMM: fixed occasional VINF_EM_TRIPLE_FAULT errors on hosts without the unrestricted guest execution feature (bug #12198)
GUI: don't bother the user with the BPP warning if no Guest Additions are installed
GUI: fixed machine-window paint artifacts on VM reboot / guest-screen resize
GUI: make sure the assigned license and description are attached to the exported appliance
GUI: fixed bugs in close VM action restrictions handling (bug #12333)
GUI: fixed incorrect wizards text colors for some unusual look and feel styles (bug #11743)
GUI: should restore seamless mode as soon as possible after VM reboot or shutdown
GUI: fixes for medium enumeration
GUI: the OS X hot corners were not accessible while a VirtualBox VM is running (Mac OS X hosts only; bug #4139)
GUI: fixed an old bug which bared the host from cleanly shutdown / reboot if the VM selector window is open (Mac OS X hosts only; bug #8254)
Host-only Networking: fixed creating of host-only network interfaces (4.3.0 regression; bug #12182)
NAT: don't run into an infinite loop in case the host cannot access any DNS server (4.3.0 regression; bug #12300)
NAT: don't re-connect the cable if the DNS information changes and the cable was disconnected before (4.3.0 regression; bug #12225)
NAT: fixed several issues with automatically starting / terminating of NAT networks on VM start / stop and configuration changes
VBoxNetDHCP: don't block prevent VBoxSVC from terminating (bug #12264)
2D Video acceleration: fix crashes on presentation mode switches (bug #9194)
BusLogic: allow to run VMs with more than one BusLogic SCSI controller enabled
Keyboard: fixed a VM crash if a VM was resumed from a saved state where at least one key was pressed (bug #11289)
VBoxSVC: fixed a heap corruption under certain conditions (4.3.0 regression)
VBoxSVC: fixed a race leading to a hang during initialization (bug #12349)
OVF: fixed import logic for OVF appliances containing multiple VMs
OVF: improved logic for finding an appropriate image format during OVF import
API: block the removal of the current snapshot if it has child snapshots (only relevant for VMs without snapshottable hard disks, their presence always prevented removal), which resulted in VM configuration corruption
API: mark VM configurations with snapshots but without current snapshot as inaccessible, as this combination is nonsense
API: fixed information for some automatically generated events (only with XPCOM, Windows host was not affected), which caused errors when getting some of the attributes over the webservice (bug #12379)
SDK: extended the functionality coverage for the C bindings
Guest Control: various bug fixes and improved VBoxManage help (bugs #8072, #11044, #12336, #12338, #12346, #12371)
Windows hosts: another attempt to fix the massive DPC latency (bug #6242)
Windows host installer: make registering file extensions optional, contributed by Tal Aloni (bug #8009)
Mac OS X hosts: properly sign the kernel extensions for Mavericks hosts (bug #12256)
Mac OS X hosts: fixed a bug where the VirtualBox dock icon was not properly removed from the dock after a VM terminated preventing Mavericks hosts from shutting down (bug #12241)
Mac OS X hosts: fixed minor installer issue (bug #12275)
Linux hosts / guests: Linux 3.13 compile fixes (bug #12358)
Linux guests: build the vboxvideo kernel module correctly on OL/RHEL 6.1 guests (bug #11996)
Linux guests: make 3D work on Slackware 14.1 (bug #12320 comments 3 and 4)
Guest Additions/3D: fixed an occasional dead-lock (bug #12319)
Windows Additions/3D: fixed possible memory leaking (bug #12228)
Windows Additions/XPDM: use separate tables containing valid video modes for each virtual monitor
Windows Additions: fixed automatic logins for Vista and newer Windows guests (bug #12332)