The default configuration of ISC BIND before 9.4.1-P1, when configured as a caching name server, allows recursive queries and provides additional delegation information to arbitrary IP addresses, which allows remote attackers to cause a denial of service (traffic amplification) via DNS queries with spoofed source IP addresses.

DNS cache poisoning via BIND, by predictable query IDs.

ISC BIND contains a data processing errors vulnerability that could allow remote attackers to cause a denial of service via TKEY queries.

Cache poisoning attacks with unsolicited RRs

Querying for records within a specially crafted zone containing certain malformed DNSKEY records can lead to CPU exhaustion.

Cache poisoning due to weak PRNG

To trigger the issue, three configuration parameters must have specific settings: "hostname-char-set" must be left at the default setting, which is "[^A-Za-z0-9.-]"; "hostname-char-replacement" must be empty (the default); and "ddns-qualifying-suffix" must NOT be empty (the default is empty). DDNS updates do not need to be enabled for this issue to manifest. A client that sends certain option content would then cause kea-dhcp4 to exit unexpectedly. This issue affects Kea versions 3.0.1 through 3.0.1 and 3.1.1 through 3.1.2.

Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why-does-my-authoritative-server-make-recursive-queries). This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1.

Invalid handling of CLASS != IN

BIND 9 server memory exhaustion during GSS-API TKEY negotiation

Multiple flaws have been identified in named related to the handling of DNS messages whose CLASS is not Internet (IN) — for example, CHAOS or HESIOD, or DNS messages that specify meta-classes (ANY or NONE) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (UPDATE), zone change notifications (NOTIFY), or processing of IN-specific record types in non-IN data — can cause assertion failures in named.

BIND servers that are configured to use TKEY-based authentication via GSS-API tokens are vulnerable to excessive memory consumption when receiving and processing maliciously-constructed packets. Typically these servers will be found in Active Directory integrated DNS deployments and/or Kerberos-secured DNS environments.

DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field

If a provably insecure domain is covered by both an NSEC and NSEC3 record at the parent, and there exist an RRSIG for only one of these types, then BIND may exit unexpectedly with an assertion while validating this proof. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

An attacker who knows (or guesses) that a resolver uses RPZ with wildcard CNAME policies can craft query names long enough to trigger a NAMETOOLONG error condition during RPZ processing. This is not handled correctly and may lead to defeating the RPZ rule. It also may lead to an unexpected exit of the BIND 9 software.

BIND may accept incorrect child-zone NSEC3 records as valid, allowing forged authenticated NXDOMAIN responses for sibling zones. AC:H (high complexity) keeps severity at Medium despite S:C.

A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the max-cache-size parameter. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

An attacker's zone can respond with an RRSIG with fewer labels than the zone it's in, causing named to produce a wildcard name shorter than the attacker's zone — resulting in cache poisoning. Requires synth-from-dnssec yes (which IS the default).

If an unauthenticated user sends a large amount of data to the Stork UI, it may cause memory and disk use problems for the system running the Stork server. This issue affects Stork versions 1.0.0 through 2.3.0.

An inapplicable NSEC record may be accepted by a named resolver as proof that no wildcard exists, which could allow an attacker at the same or an upstream level of the zone name to mask the existence of a victim's wildcard record. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

If BIND is loaded with a "named.conf" file that contains no global "options" block, an attacker can send a query of QTYPE TKEY which may cause an assertion failure and subsequent unexpected program exit. This issue affects BIND 9 versions 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and 9.20.9-S1 through 9.20.27-S1.

A BIND resolver encountering an SVCB/HTTPS AliasMode record referencing 14 or more SVCB/HTTPS ServiceMode records may fail to properly deallocate internal resources. If this happens repeatedly, resource exhaustion will eventually prevent the resolver from performing new recursive lookups. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

A BIND recursive resolver may experience excessive resource consumption if it encounters large numbers of a particular kind of invalid DNSSEC record. Default limits on "max-records-per-type" and "max-types-per-name" help mitigate the exposure. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

If a BIND resolver sends a query for a DNSSEC-signed authoritative zone, and the authoritative server replies with a valid wildcard answer and signed NSEC3 proof, followed by an unsigned NSEC at the same owner name, it will trigger an unexpected program exit. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

A malformed zone may contain an NS or DNAME node above its origin, which named treats as a zone cut. If an attacker inserts a malformed zone into a BIND authoritative server (e.g., via zone transfer), queries for names inside the configured zone then lose authoritative status and return an out-of-zone delegation. On a server that also provides recursion BIND can follow this locally sourced cut and cache attacker-supplied data, affecting names outside the configured zone. This situation persists as long as the malformed zone remains in the zone database. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

Buffer overflow in host command allows a remote attacker to execute arbitrary commands via a long response to an AXFR query.

named in BIND 8.2 through 8.2.2-P6 allows remote attackers to cause a denial of service by sending an SRV record to the server, aka the "srv bug."

named in BIND 8.2 through 8.2.2-P6 allows remote attackers to cause a denial of service by making a compressed zone transfer (ZXFR) request and performing a name service query on an authoritative record that is not cached, aka the "zxfr bug."

On a resolver configured to use dns64, if an applicable answer from the authoritative server is malformed in a specific way, the resolver named process will exit unexpectedly. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.