The xhci_kick_epctx function in hw/usb/hcd-xhci.c in QEMU (aka Quick Emulator) allows local guest OS privileged users to cause a denial of service (infinite loop and QEMU process crash) via vectors related to control transfer descriptor sequence. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2017-5973