OpenBSD PF IP Fragment Remote DoS

This module exploits the following vulnerability, as described by the CVE database: "A logic error in the IP fragment cache functionality in pf in FreeBSD 5.3, 5.4, and 6.0, and OpenBSD, when a 'scrub fragment crop' or 'scrub fragment drop-ovl' rule is being used, allows remote attackers to cause a denial of service (crash) via crafted packets that cause a packet fragment to be inserted twice."