FreeBSD Security Advisory FreeBSD-SA-04:06.ipv6 – Applications may manipulate the behavior of an IPv6 socket using the setsockopt(2) system call. This may allow a local attacker to read portions of kernel memory.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/32975/FreeBSD-SA-04%3A06.ipv6.txt
Source: https://packetstormsecurity.com/files/32975/FreeBSD-Security-Advisory-2004.6.html