The Neighbor Discovery (ND) protocol implementation in the IPv6 stack in FreeBSD through 10.1 allows remote attackers to reconfigure a hop-limit setting via a small hop_limit value in a Router Advertisement (RA) message.
https://www.freebsd.org/security/advisories/FreeBSD-SA-15:09.ipv6.asc
https://lists.freebsd.org/pipermail/freebsd-net/2015-April/041934.html