The esp_reg_write function in hw/scsi/esp.c in the 53C9X Fast SCSI Controller (FSC) support in QEMU does not properly check command buffer length, which allows local guest OS administrators to cause a denial of service (out-of-bounds write and QEMU process crash) or potentially execute arbitrary code on the QEMU host via unspecified vectors. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-4439
