OpenSSH Security Advisory
An OpenSSH Security Advisory (partially quoted below) was released a few hours ago. Markus Friedl (markus@) found and fixed the issue in this commit. The change has also been back-ported to OpenBSD 5.4, and OpenBSD 5.3 has been upgraded to OpenSSH 6.4 to fix this issue. Errata for OpenBSD 5.4 and OpenBSD 5.3 have been updated, and patches are available.
You don't need to be a genius to debug a pf.conf firewall ruleset, you just need the guts to run tcpdump