conntrackd in conntrack-tools 1.4.2 and earlier does not ensure that the optional kernel modules are loaded before using them, which allows remote attackers to cause a denial of service (crash) via a (1) DCCP, (2) SCTP, or (3) ICMPv6 packet. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6496