The ipsec4_get_ulp function in the kernel in NetBSD 2.0 through 3.1 and NetBSD-current before 20071028, when the fast_ipsec subsystem is enabled, allows remote attackers to bypass the IPsec policy by sending packets from a source machine with a different endianness than the destination machine, a different vulnerability than CVE-2006-0905.

A "programming error" in fast_ipsec in FreeBSD 4.8-RELEASE through 6.1-STABLE and NetBSD 2 through 3 does not properly update the sequence number associated with a Security Association, which allows packets to pass sequence number checks and allows remote attackers to capture IPSec packets and conduct replay attacks.