Red Hat Security Advisory 2015-1044-01 – The virtio-win package provides paravirtualized network drivers for most Microsoft Windows operating systems. Paravirtualized drivers are virtualization-aware drivers used by fully virtualized guests running on Red Hat Enterprise Linux. Fully virtualized guests using the paravirtualized drivers gain significantly better I/O performance than fully virtualized guests running without the drivers. It was found that the Windows Virtio NIC driver did not sufficiently sanitize the length of the incoming IP packets, as demonstrated by a packet with IP options present but the overall packet length not being adjusted to reflect the length of those options. A remote attacker able to send a specially crafted IP packet to the guest could use this flaw to crash that guest.