FreeBSD Security Advisory – In case of an incoming ICMPv6 ‘Packet Too Big Message’, there is an insufficient check on the proposed new MTU for a path to the destination. When the kernel is configured to process IPv6 packets and has active IPv6 TCP sockets, a specifically crafted ICMPv6 ‘Packet Too Big Message’ could cause the TCP stack of the kernel to panic.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/69619/FreeBSD-SA-08-09.icmp6.txt
Source: https://packetstormsecurity.com/files/69619/FreeBSD-SA-08-09.icmp6.txt.html