FreeBSD Security Advisory FreeBSD-SA-05:19.ipsec – IPsec is a security protocol for the Internet Protocol networking layer. It provides a combination of encryption and authentication of system, using several possible cryptography algorithms. A programming error in the implementation of the AES-XCBC-MAC algorithm for authentication resulted in a constant key being used instead of the key specified by the system administrator.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/38928/FreeBSD-SA-05-19.ipsec.txt
Source: https://packetstormsecurity.com/files/38928/FreeBSD-SA-05-19.ipsec.txt.html