The SIOCGIFCONF ioctl (ifconf function) in FreeBSD 4.x through 4.11 and 5.x through 5.4 does not properly clear a buffer before using it, which allows local users to obtain portions of sensitive kernel memory.
https://exchange.xforce.ibmcloud.com/vulnerabilities/20114
http://www.vupen.com/english/advisories/2005/2256
http://www.securityfocus.com/bid/15252
http://secunia.com/advisories/17368
http://secunia.com/advisories/14959
http://lists.apple.com/archives/security-announce/2005/Oct/msg00000.html