QEMU 0.9.0 allows local users of a Windows XP SP2 guest operating system to overwrite the TranslationBlock (code_gen_buffer) buffer, and probably have unspecified other impacts related to an "overflow," via certain Windows executable programs, as demonstrated by qemu-dos.com.
https://exchange.xforce.ibmcloud.com/vulnerabilities/38806
http://www.securityfocus.com/bid/26666
http://www.securityfocus.com/archive/1/484429/100/0/threaded
http://www.mandriva.com/security/advisories?name=MDVSA-2008:162