PowerDNS before 2.9.18, when running with an LDAP backend, does not properly escape LDAP queries, which allows remote attackers to cause a denial of service (failure to answer ldap questions) and possibly conduct an LDAP injection attack.
PowerDNS before 2.9.18, when allowing recursion to a restricted range of IP addresses, does not properly handle questions from clients that are denied recursion, which could cause a "blank out" of answers to those clients that are allowed to use recursion.