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