Security update for OpenBSD fixes problem with ICMP6 packets
The developers of OpenBSD have released a patch which fixes a vulnerability in the processing of ICMP6 packets. It appears that a buffer was being incorrectly handled. The developers do not divulge, in their extremely brief notification, how the bug occurs and whether a system can be compromised by it or merely crashed. Where it is not possible to install the patch, they recommend filtering out ICMP6 packets.
Back in early January, the developers patched a bug in the TCP/IPv6 stack, with which the ICMP6 echo request - ping packets - could trip the kernel into an infinite loop. This bug was not, however, classified as being security related, even though it could have been used to shut down the server.
- OpenBSD 4.0 release errata & patch list, bug list from OpenBSD