The ASN.1 parser (pluto/asn1.c, libstrongswan/asn1/asn1.c, libstrongswan/asn1/asn1_parser.c) in (a) strongSwan 2.8 before 2.8.10, 4.2 before 4.2.16, and 4.3 before 4.3.2; and (b) openSwan 2.6 before 2.6.22 and 2.4 before 2.4.15 allows remote attackers to cause a denial of service (pluto IKE daemon crash) via an X.509 certificate with (1) crafted Relative Distinguished Names (RDNs), (2) a crafted UTCTIME string, or (3) a crafted GENERALIZEDTIME string.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.