The MSI-X MMIO support in hw/pci/msix.c in QEMU (aka Quick Emulator) allows local guest OS privileged users to cause a denial of service (NULL pointer dereference and QEMU process crash) by leveraging failure to define the .write method.
git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=43b11a91dd861a946b231b89b754285
lists.fedoraproject.org/pipermail/package-announce/2016-January/175380.html
www.debian.org/security/2016/dsa-3471
www.openwall.com/lists/oss-security/2015/12/14/2
www.securityfocus.com/bid/80761
bugzilla.redhat.com/show_bug.cgi?id=1291137
security.gentoo.org/glsa/201602-01