The Internet Key Exchange version 1 (IKEv1) implementation (isakmp_agg.c) in the Shoichi Sakane KAME Project racoon, as used by NetBSD 1.6, 2.x before 20060119, certain FreeBSD releases, and possibly other distributions of BSD or Linux operating systems, when running in aggressive mode, allows remote attackers to cause a denial of service (daemon crash) via crafted IKE packets, as demonstrated by the PROTOS ISAKMP Test Suite for IKEv1.