A complete revision history is at the end of this file. Exploitation details involving this vulnerability have been widely distributed. We will update this advisory as we receive additional information. Please check advisory files regularly for updates that relate to your site. It is known that some systems will react in an unpredictable fashion when receiving oversized IP packets.
Reports indicate a range of reactions including crashing, freezing, and rebooting.
Many ping implementations by default send ICMP datagrams consisting only of the 8 octets of ICMP header information but allow the user to specify a larger packet size if desired. You can read more information about this vulnerability on Mike Bremford's Web page. Impact Systems receiving oversized ICMP datagrams may crash, freeze, or reboot, resulting in denial of service. Solution First, since crashing a router or firewall may be part of a larger, multistage attack scenario, we encourage you to inspect the running configuration of any such systems that have crashed to ensure that the configuration information is what you expect it to be. Then install a patch from your vendor.