IKEv2 in strongSwan 4.0.7 before 5.1.3 allows remote attackers to bypass authentication by rekeying an IKESA during (1) initiation or (2) re-authentication, which triggers the IKESA state to be set to established.

charon/sa/tasks/childcreate.c in the charon daemon in strongSWAN before 4.3.1 switches the NULL checks for TSi and TSr payloads, which allows remote attackers to cause a denial of service via an IKEAUTH request without a (1) TSi or (2) TSr traffic selector.

charon/sa/ikesa.c in the charon daemon in strongSWAN before 4.3.1 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via an invalid IKESAINIT request that triggers "an incomplete state," followed by a CREATECHILDSA request.

The pluto IKE daemon in Openswan and Strongswan IPsec 2.6 before 2.6.21 and 2.4 before 2.4.14, and Strongswan 4.2 before 4.2.14 and 2.8 before 2.8.9, allows remote attackers to cause a denial of service (daemon crash and restart) via a crafted (1) RUTHERE or (2) RUTHEREACK Dead Peer Detection (DPD) IPsec IKE Notification message that triggers a NULL pointer dereference related to inconsistent ISAKMP state and the lack of a phase2 state association in DPD.