The Internet Key Exchange version 1 (IKEv1) implementation (isakmp_agg.c) in racoon in ipsec-tools before 0.6.3, when running in aggressive mode, allows remote attackers to cause a denial of service (null dereference and crash) via crafted IKE packets, as demonstrated by the PROTOS ISAKMP Test Suite for IKEv1.
Weaknesses in this category are related to improper management of system resources.