FreeS/WAN 1.x and 2.x, and other related products including superfreeswan 1.x, openswan 1.x before 1.0.6, openswan 2.x before 2.1.4, and strongSwan before 2.1.3, allows remote attackers to authenticate using spoofed PKCS#7 certificates in which a self-signed certificate identifies an alternate Certificate Authority (CA) and spoofed issuer and subject.

IPSEC implementations including (1) FreeS/WAN and (2) KAME do not properly calculate the length of authentication data, which allows remote attackers to cause a denial of service (kernel panic) via spoofed, short Encapsulating Security Payload (ESP) packets, which result in integer signedness errors.