QEMU 0.8.2 allows local users to crash a virtual machine via the divisor operand to the aam instruction, as demonstrated by "aam 0x0," which triggers a divide-by-zero error.
https://exchange.xforce.ibmcloud.com/vulnerabilities/34046
http://www.vupen.com/english/advisories/2007/1597
http://www.securityfocus.com/bid/23731
http://www.mandriva.com/security/advisories?name=MDVSA-2008:162
http://www.debian.org/security/2007/dsa-1284
http://taviso.decsystem.org/virtsec.pdf
http://secunia.com/advisories/29129
http://secunia.com/advisories/25095
http://secunia.com/advisories/25073
http://lists.gnu.org/archive/html/qemu-devel/2007-04/msg00651.html
http://lists.gnu.org/archive/html/qemu-devel/2007-04/msg00650.html