hw/ide/core.c in QEMU does not properly restrict the commands accepted by an ATAPI device, which allows guest users to cause a denial of service or possibly have unspecified other impact via certain IDE commands, as demonstrated by a WIN_READ_NATIVE_MAX command to an empty drive, which triggers a divide-by-zero error and instance crash. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6855
