Unbound before 1.3.4 does not properly verify signatures for NSEC3 records, which allows remote attackers to cause secure delegations to be downgraded via DNS spoofing or other DNS-related attacks in conjunction with crafted delegation responses.
osvdb.org/58836
secunia.com/advisories/36996
secunia.com/advisories/37913
unbound.net/pipermail/unbound-users/2009-October/000852.html
www.debian.org/security/2009/dsa-1963
www.openwall.com/lists/oss-security/2009/10/09/2
www.openwall.com/lists/oss-security/2009/10/09/3
www.vupen.com/english/advisories/2009/2875
exchange.xforce.ibmcloud.com/vulnerabilities/53729