The libarchive library in FreeBSD 6-STABLE after 2006-09-05 and before 2006-11-08 allows context-dependent attackers to cause a denial of service (CPU consumption) via a malformed archive that causes libarchive to skip a region past the actual end of the archive, which triggers an infinite loop that attempts to read more data.
https://exchange.xforce.ibmcloud.com/vulnerabilities/30137
http://www.securityfocus.com/bid/20961
http://securitytracker.com/id?1017199