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 5.7.0 performs many TCP reconnections upon receiving certain nonsensical responses from servers.
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.
DNSSEC validation is not performed correctly. An attacker can cause this package to report successful validation for invalid, attacker-controlled records. Root DNSSEC public keys are not validated, permitting an attacker to present a self-signed root key and delegation chain.
DNSSEC validation is not performed correctly. An attacker can cause this package to report successful validation for invalid, attacker-controlled records. The owner name of RRSIG RRs is not validated, permitting an attacker to present the RRSIG for an attacker-controlled domain in a response for any other domain.
Knot Resolver through 5.5.1 may allow DNS cache poisoning when there is an attempt to limit forwarding actions by filters.
A flaw was found in knot-resolver before version 2.3.0. Malformed DNS messages may cause denial of service.
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.
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
Cache Poisoning issue exists in DNS Response Rate Limiting.
A vulnerability was discovered in DNS resolver of knot resolver before version 4.1.0 which allows remote attackers to downgrade DNSSEC-secure domains to DNSSEC-insecure state, opening possibility of domain hijack using attacks against insecure DNS protocol.
A vulnerability was discovered in DNS resolver component of knot resolver through version 3.2.0 before 4.1.0 which allows remote attackers to bypass DNSSEC validation for non-existence answer. NXDOMAIN answer would get passed through to the client even if its DNSSEC validation failed, instead of sending a SERVFAIL packet. Caching is not affected by this particular bug but see CVE-2019-10191.
Improper input validation bug in DNS resolver component of Knot Resolver before 2.4.1 allows remote attacker to poison cache.
Improper input validation bugs in DNSSEC validators components in Knot Resolver (prior version 1.5.2) allow attacker in man-in-the-middle position to deny existence of some data in DNS via packet replay.