The process_tx_desc function in hw/net/e1000.c in QEMU before 2.4.0.1 does not properly process transmit descriptor data when sending a network packet, which allows attackers to cause a denial of service (infinite loop and guest crash) via unspecified vectors.
https://www.arista.com/en/support/advisories-notices/security-advisories/1188-security-advisory-14
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg05832.html
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg01199.html
https://bugzilla.redhat.com/show_bug.cgi?id=1260076
http://www.ubuntu.com/usn/USN-2745-1
http://www.openwall.com/lists/oss-security/2015/09/05/5
http://www.openwall.com/lists/oss-security/2015/09/04/4
http://lists.opensuse.org/opensuse-security-announce/2015-11/msg00011.html
http://lists.opensuse.org/opensuse-security-announce/2015-11/msg00005.html
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00026.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-October/168671.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-October/168646.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-October/168077.html