Hickory DNS hickory-net 0.26.0 before 0.26.2 and hickory-proto 0.25.0 through 0.25.2 skip the check that a UDP response's question section matches the query when the response has an empty question section (QDCOUNT=0), and also skip the case-randomization check. Remote attackers able to inject spoofed UDP responses can send QDCOUNT=0 responses to bypass these checks, weakening defenses against DNS spoofing.