The DNS implementation of PowerDNS 2.9.16 and earlier allows remote attackers to cause a denial of service via a compressed DNS packet with a label length byte with an incorrect offset, which could trigger an infinite loop.

The DNSPacket::expand method in dnspacket.cc in PowerDNS before 2.9.17 allows remote attackers to cause a denial of service by sending a random stream of bytes.

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 2.9.21.2 allows remote attackers to cause a denial of service (daemon crash) via a CH HINFO query.

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.