Unbound before 1.4.3 does not properly align structures on 64-bit platforms, which allows remote attackers to cause a denial of service (daemon crash) via unspecified vectors.
http://www.unbound.net/pipermail/unbound-users/2010-March/001057.html
http://www.securityfocus.com/bid/38701
http://www.openwall.com/lists/oss-security/2010/03/12/3
http://secunia.com/advisories/38888