The server implementation of the EAP-MSCHAPv2 protocol in the eap-mschapv2 plugin in strongSwan 4.2.12 through 5.x before 5.3.4 does not properly validate local state, which allows remote attackers to bypass authentication via an empty Success message in response to an initial Challenge message.

strongSwan 4.3.0 through 5.x before 5.3.2 and strongSwan VPN Client before 1.4.6, when using EAP or pre-shared keys for authenticating an IKEv2 connection, does not enforce server authentication restrictions until the entire authentication process is complete, which allows remote servers to obtain credentials by using a valid certificate and then reading the responses.

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

The compare_dn function in utils/identification.c in strongSwan 4.3.3 through 5.1.1 allows (1) remote attackers to cause a denial of service (out-of-bounds read, NULL pointer dereference, and daemon crash) or (2) remote authenticated users to impersonate arbitrary users and bypass access restrictions via a crafted ID_DER_ASN1_DN ID, related to an "insufficient length check" during identity comparison.

Buffer overflow in the atodn function in strongSwan 2.0.0 through 4.3.4, when Opportunistic Encryption is enabled and an RSA key is being used, allows remote attackers to cause a denial of service (pluto IKE daemon crash) and possibly execute arbitrary code via crafted DNS TXT records. NOTE: this might be the same vulnerability as CVE-2013-2053 and CVE-2013-2054.

The GMP Plugin in strongSwan 4.2.0 through 4.6.3 allows remote attackers to bypass authentication via a (1) empty or (2) zeroed RSA signature, aka "RSA signature verification vulnerability."

The IKE daemon in strongSwan 4.3.x before 4.3.7 and 4.4.x before 4.4.1 does not properly check the return values of snprintf calls, which allows remote attackers to execute arbitrary code via crafted (1) certificate or (2) identity data that triggers buffer overflows.