Certain DNSSEC aspects of the DNS protocol (in RFC 4033, 4034, 4035, 6840, and related RFCs) allow remote attackers to cause a denial of service (CPU consumption) via one or more DNSSEC responses, aka the "KeyTrap" issue. One of the concerns is that, when there is a zone with many DNSKEY and RRSIG records, the protocol specification implies that an algorithm must evaluate all combinations of DNSKEY and RRSIG records.
Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification attacks and potentially causing a denial of service. Specifically, a single client query may lead to a hundred TCP connection attempts if a DNS server closes connections without providing a response.
Knot Resolver before 5.5.3 allows remote attackers to cause a denial of service (CPU consumption) because of algorithmic complexity. During an attack, an authoritative server must return large NS sets or address sets.
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
BIRD through 2.0.7 does not provide functionality for password authentication of BGP peers. Because of this, products that use BIRD (which may, for example, include Tigera products in some configurations, as well as products of other vendors) may have been susceptible to route redirection for Denial of Service and/or Information Disclosure. NOTE: a researcher has asserted that the behavior is within Tigera’s area of responsibility; however, Tigera disagrees
Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an "NXNSAttack" issue. This is triggered by random subdomains in the NSDNAME in NS records.