sys/netinet6/icmp6.c in the kernel in FreeBSD 6.3 through 7.1, NetBSD 3.0 through 4.0, and possibly other operating systems does not properly check the proposed new MTU in an ICMPv6 Packet Too Big Message, which allows remote attackers to cause a denial of service (panic) via a crafted Packet Too Big Message.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.