I found this bugreport in launchpad. It can be found here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/360926 Doing "ip link set $IFACE promisc on multicast on" solves it.
"ip link set $IFACE promisc on multicast on" does not solve the problem for me, at least not for IPv6 autoconfiguration packets. They don't work at all.