The ehci_process_itd function in hw/usb/hcd-ehci.c in QEMU allows local guest OS administrators to cause a denial of service (infinite loop and CPU consumption) via a circular isochronous transfer descriptor (iTD) list.
git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=156a2e4dbffa85997636a7a39ef12da6f1b40254
www.debian.org/security/2016/dsa-3469
www.debian.org/security/2016/dsa-3470
www.debian.org/security/2016/dsa-3471
www.openwall.com/lists/oss-security/2015/12/14/16
www.openwall.com/lists/oss-security/2015/12/14/9
www.securityfocus.com/bid/80694
bugzilla.redhat.com/show_bug.cgi?id=1277983
lists.gnu.org/archive/html/qemu-devel/2015-12/msg02124.html
security.gentoo.org/glsa/201602-01