FreeBSD Security Advisory – By crafting malicious BGP packets, an attacker could exploit a vulnerability in tcpdump allowing them to execute code or crash the process.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/58299/FreeBSD-SA-07-06.tcpdump.txt
Source: https://packetstormsecurity.com/files/58299/FreeBSD-SA-07-06.tcpdump.txt.html