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.

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 a provably insecure domain is covered by both NSEC and NSEC3 at the parent, with an RRSIG for only one type, BIND exits with an assertion during validation.

In a BIND resolver, inbound DNS protocol messages with a particular structure will result in additional processing, with no limit imposed by BIND. A DNS message with a maliciously large number of such structures will cause BIND to consume disproportionate amounts of CPU time and memory during processing.

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.

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.

Invalid handling of CLASS != IN

BIND 9 server memory exhaustion during GSS-API TKEY negotiation

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.

A recursive BIND server that receives a query with recursion desired (RD=1) followed by a non-recursive query (RD=0) may exit with an assertion failure, resulting in a denial of service. To be vulnerable, the BIND server must allow recursive queries and have at least two RPZ zones configured: one with the default setting of "recursive-only yes", and the other with "recursive-only no".

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.

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

Last updated 19 August 2026

Last updated 19 August 2026

If BIND encounters a particular invalid data structure in a DNS record, it will accept the invalid data, and may subsequently abort and exit.

A flaw was found in Bind, where a resolver crash is possible. When stale cache and stale answers are enabled, the option stale-answer-client-timeout is set to a positive integer, and the resolver receives an RRSIG query.

A flaw was found in Bind. When resolver receives many queries requiring recursion, there will be a corresponding increase in the number of clients waiting for recursion to complete. This may, under certain conditions, lead to an assertion failure and a denial of service.

A flaw was found in the Bind package, where the resolver can crash when stale cache and stale answers are enabled, option stale-answer-client-timeout is set to 0 and there is a stale CNAME in the cache for an incoming query. By sending specific queries to the resolver, an attacker can cause named to crash.

A flaw was found in Bind, where sending a flood of dynamic DNS updates may cause named to allocate large amounts of memory. This issue may cause named to exit due to a lack of free memory, resulting in a denial of service (DoS).

An attacker can leverage this flaw to gradually erode available memory to the point where named crashes for lack of resources. Upon restart the attacker would have to begin again, but nevertheless there is the potential to deny service.

A flaw was found in the Bind package, where the DNSSEC verification code for the EdDSA algorithm leaks memory when there is a signature length mismatch. By spoofing the target resolver with responses that have a malformed EdDSA signature, an attacker can trigger a small memory leak, resulting in crashing the program.

The underlying bug might cause read past end of the buffer and either read memory it should not read, or crash the process.

A flaw was found in the Bind package. By spoofing the target resolver with responses that have a malformed ECDSA signature, an attacker can trigger a small memory leak, resulting in crashing the program.

On vulnerable configurations, the named daemon may, in some circumstances, terminate with an assertion failure. Vulnerable configurations are those that include a reference to http within the listen-on statements in their named.conf. TLS is used by both DNS over TLS (DoT) and DNS over HTTPS (DoH), but configurations using DoT alone are unaffected. Affects BIND 9.18.0 -> 9.18.2 and version 9.19.0 of the BIND 9.19 development branch.

When the vulnerability is triggered the BIND process will exit. BIND 9.18.0

Versions affected: BIND 9.18.0 When a vulnerable version of named receives a series of specific queries, the named process will eventually terminate due to a failed assertion check.

A flaw was found in Bind that incorrectly handles certain crafted TCP streams. The vulnerability allows TCP connection slots to be consumed for an indefinite time frame via a specifically crafted TCP stream sent from a client. This flaw allows a remote attacker to send specially crafted TCP streams with 'keep-response-order' enabled that could cause connections to BIND to remain in CLOSEWAIT status for an indefinite period, even after the client has terminated the connection. This issue results in BIND consuming resources, leading to a denial of service.

A flaw was found in bind. When flooding the target resolver with special queries, an attacker can significantly impair the resolver's performance, effectively denying legitimate clients access to the DNS resolution service.