ISC BIND BIND is an open source DNS server. It was the first DNS server, and is maintained by the Internet Systems Consortium

BIND 9.11-9.21 NSEC "Next Domain" DNS Zone Validation Flaw
CVE-2026-13321 8.6 - High - July 22, 2026

The BIND resolver accepts validly-signed NSEC records where the "Next Domain Name" field points outside the signer's zone. 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.

Origin Validation Error

BIND 9 DNS Crash: NSEC/NSEC3 RRSIG Mismatch (v9.11-9.21)
CVE-2026-13204 7.5 - High - July 22, 2026

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.

assertion failure

BIND 9 'named' Crash on DNAME/A Record Race (9.18.x-9.20.x)
CVE-2026-12617 7.5 - High - July 22, 2026

The issue is unexpected program termination based on ordering and/or specific content in responses to queries for CNAME or DNAME, and A records. Specifically, if a client queries for a DNAME and A record below the DNAME to the resolver, and the authoritative server responds positively to the A query but delays the DNAME response and later responds negatively, `named` may quit unexpectedly. Or, if a client queries for a CNAME and A record for the same name to the resolver, and the authoritative server responds positively to the A query but delays the CNAME response and later responds with a self-referential CNAME, the same failure may occur. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

assertion failure

BIND9 Cache Poison via RRSIG Label Mismatch (9.11-9.21.23)
CVE-2026-11721 7.5 - High - July 22, 2026

It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). 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.

Improper Validation of Specified Quantity in Input

Memory bloat via DNSSEC subdom attack on ISC BIND 9 (9.18.50/9.20.24/9.21.23)
CVE-2026-11622 7.5 - High - July 22, 2026

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.

Allocation of Resources Without Limits or Throttling

Resource Exhaustion via DNSSEC RRSIG Validation in BIND 9 9.20.x-9.21.x
CVE-2026-11605 7.5 - High - July 22, 2026

The issue is a resource exhaustion vulnerability associated with DNSSEC validation. BIND always validates all RRSIG records in an answer, even if they are not strictly needed. A query to an authoritative server/zone which returns many valid but superfluous RRSIG records causes the validator to waste disproportionate CPU time. This issue affects BIND 9 versions 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, and 9.20.9-S1 through 9.20.24-S1.

Incorrect Behavior Order: Early Amplification

BIND9 RPZ wildcard CNAME NAMETOOLONG error 9.16-9.21
CVE-2026-11331 7.5 - High - July 22, 2026

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. This issue affects BIND 9 versions 9.16.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.16.8-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

Improper Filtering of Special Elements

BIND 9 PRIVATEDNS Length Mischeck (9.18.09.21.23)
CVE-2026-10822 6.5 - Medium - July 22, 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. BIND will first need to store a DNS record for a key (KEY, DNSKEY, etc.). That key must specify a PRIVATEDNS algorithm (253), and in the algorithm identifier, improperly give a length longer than the actual identifier data. The invalid identifier will be stored. If BIND later needs to render that record to text, it will use the invalid length during processing, leading to a consistency check failing. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

assertion failure

BIND 9 NSEC3 AuthNXDOMAIN Forgery (Affected 9.18.0-9.21.23)
CVE-2026-10723 6.8 - Medium - July 22, 2026

BIND may accept incorrect child-zone NSEC3 records as valid, which could allow an attacker to forge authenticated NXDOMAIN responses. This issue affects BIND 9 versions 9.18.0 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.

Improper Verification of Cryptographic Signature

BIND 9 Unbounded Resend Loop Causing Resource Exhaustion (9.18.369.18.48)
CVE-2026-5950 5.3 - Medium - May 20, 2026

An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Unchecked Input for Loop Condition

BIND9 9.20.0-9.21.21/use-after-free via SIG(0) race during recursiveclient limit
CVE-2026-5947 7.5 - High - May 20, 2026

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

Race Condition

BIND 9 named Assertion Failure on Non-IN DNS Messages 9.119.21 CVE-2026-5946
CVE-2026-5946 7.5 - High - May 20, 2026

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`. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Improper Input Validation

Use-After-Free in BIND 9 DoH (9.20.09.20.22 / 9.21.09.21.21)
CVE-2026-3593 7.4 - High - May 20, 2026

A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.

Dangling pointer

Amplified Resource Consumption in BIND 9 Resolvers (9.11-9.21.21)
CVE-2026-3592 5.3 - Medium - May 20, 2026

BIND resolvers are vulnerable to an amplified resource consumption/exhaustion attack. If a victim resolver makes a query to a specially crafted zone, the resolver will consume disproportionate resources. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Incorrect Behavior Order: Early Amplification

BIND 9 TKEY GSS-API Excessive Mem (9.16.50/9.18.48/9.20.22/9.21.21)
CVE-2026-3039 7.5 - High - May 20, 2026

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. This issue affects BIND 9 versions 9.0.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.9.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Missing Reference to Active Allocated Resource

Use-After-Return in ISC BIND 9 named for SIG(0) (9.20.020, 9.21.019, 9.20.9S120)
CVE-2026-3591 5.4 - Medium - March 25, 2026

A use-after-return vulnerability exists in the `named` server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.

Return of Stack Variable Address

BIND 9 Crash via Signed TSIG TKEY Query (9.20.0 9.21.19)
CVE-2026-3119 6.5 - Medium - March 25, 2026

Under certain conditions, `named` may crash when processing a correctly signed query containing a TKEY record. The affected code can only be reached if an incoming request has a valid transaction signature (TSIG) from a key declared in the `named` configuration. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.

assertion failure

ISC BIND 9 9.20.09.20.20 Memory Leak via Crafted Domain
CVE-2026-3104 7.5 - High - March 25, 2026

A specially crafted domain can be used to cause a memory leak in a BIND resolver simply by querying this domain. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.

Missing Release of Resource after Effective Lifetime

BIND 9 DNSSEC Zone Crafting CPU Exhaustion (9.11-9.21)
CVE-2026-1519 7.5 - High - March 25, 2026

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.

Unchecked Input for Loop Condition

BIND 9 9.18.40-43, 9.20.13-17, 9.21.12-16 named crash via malformed BRID/HHIT
CVE-2025-13878 7.5 - High - January 21, 2026

Malformed BRID/HHIT records can cause `named` to terminate unexpectedly. This issue affects BIND 9 versions 9.18.40 through 9.18.43, 9.20.13 through 9.20.17, 9.21.12 through 9.21.16, 9.18.40-S1 through 9.18.43-S1, and 9.20.13-S1 through 9.20.17-S1.

assertion failure

BIND 9 PRNG flaw predicts source port/query ID (before 9.21.13/S1)
CVE-2025-40780 8.6 - High - October 22, 2025

In specific circumstances, due to a weakness in the Pseudo Random Number Generator (PRNG) that is used, it is possible for an attacker to predict the source port and query ID that BIND will use. This issue affects BIND 9 versions 9.16.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.16.8-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

Predictable from Observable State

Cache Injection via Lenient Record Acceptance in BIND 9 (up to 9.21.12)
CVE-2025-40778 8.6 - High - October 22, 2025

Under certain circumstances, BIND is too lenient when accepting records from answers, allowing an attacker to inject forged data into the cache. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

Acceptance of Extraneous Untrusted Data With Trusted Data

CPU Exhaustion via Malformed DNSKEY in BIND 9 (9.189.21)
CVE-2025-8677 7.5 - High - October 22, 2025

Querying for records within a specially crafted zone containing certain malformed DNSKEY records can lead to CPU exhaustion. This issue affects BIND 9 versions 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

Amplification

CNAME Chain Assertion Failure in BIND 9 9.20.0–9.20.10 Caching Resolver
CVE-2025-40777 7.5 - High - July 16, 2025

If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable value other than `disabled`), and if the resolver, in the process of resolving a query, encounters a CNAME chain involving a specific combination of cached or authoritative records, the daemon will abort with an assertion failure. This issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through 9.21.9, and 9.20.9-S1 through 9.20.10-S1.

assertion failure

Cache Poisoning in BIND 9 (named) before 9.20.10 via ECS
CVE-2025-40776 8.6 - High - July 16, 2025

A `named` caching resolver that is configured to send ECS (EDNS Client Subnet) options may be vulnerable to a cache-poisoning attack. This issue affects BIND 9 versions 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.37-S1, and 9.20.9-S1 through 9.20.10-S1.

DoS via Excessive ADDITIONAL Records in ISC BIND 9 (9.1121.3)
CVE-2024-11187 7.5 - High - January 29, 2025

It is possible to construct a zone such that some queries to it will generate responses containing numerous records in the Additional section. An attacker sending many such queries can cause either the authoritative server itself or an independent resolver to use disproportionate resources processing the queries. Zones will usually need to have been deliberately crafted to attack this exposure. This issue affects BIND 9 versions 9.11.0 through 9.11.37, 9.16.0 through 9.16.50, 9.18.0 through 9.18.32, 9.20.0 through 9.20.4, 9.21.0 through 9.21.3, 9.11.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.50-S1, and 9.18.11-S1 through 9.18.32-S1.

BIND 9 TCP Flood Leads to Instability (9.18.19.18.27, 9.19.09.19.24)
CVE-2024-0760 7.5 - High - July 23, 2024

A malicious client can send many DNS messages over TCP, potentially causing the server to become unstable while the attack is in progress. The server may recover after the attack ceases. Use of ACLs will not mitigate the attack. This issue affects BIND 9 versions 9.18.1 through 9.18.27, 9.19.0 through 9.19.24, and 9.18.11-S1 through 9.18.27-S1.

BIND 9.11-9.19 RR Caching Overwrite Performance Degradation
CVE-2024-1737 7.5 - High - July 23, 2024

Resolver caches and authoritative zone databases that hold significant numbers of RRs for the same hostname (of any RTYPE) can suffer from degraded performance as content is being added or updated, and also when handling client queries for this name. This issue affects BIND 9 versions 9.11.0 through 9.11.37, 9.16.0 through 9.16.50, 9.18.0 through 9.18.27, 9.19.0 through 9.19.24, 9.11.4-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.50-S1, and 9.18.11-S1 through 9.18.27-S1.

BIND 9 (9.16.13-9.19.24) Local Zone Lookup Assertion Failure (CVE-2024-4076)
CVE-2024-4076 - July 23, 2024

Client queries that trigger serving stale data and that also require lookups in local authoritative zone data may result in an assertion failure. This issue affects BIND 9 versions 9.16.13 through 9.16.50, 9.18.0 through 9.18.27, 9.19.0 through 9.19.24, 9.11.33-S1 through 9.11.37-S1, 9.16.13-S1 through 9.16.50-S1, and 9.18.11-S1 through 9.18.27-S1.

DNSSEC KeyTrap DoS via DNSKEY/RRSIG overevaluation in BIND 9
CVE-2023-50387 7.5 - High - February 14, 2024

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.

Allocation of Resources Without Limits or Throttling

BIND 9 9.16.09.16.45 cachedatabase cleanup leads to memory exhaustion
CVE-2023-6516 7.5 - High - February 13, 2024

To keep its cache database efficient, `named` running as a recursive resolver occasionally attempts to clean up the database. It uses several methods, including some that are asynchronous: a small chunk of memory pointing to the cache element that can be cleaned up is first allocated and then queued for later processing. It was discovered that if the resolver is continuously processing query patterns triggering this type of cache-database maintenance, `named` may not be able to handle the cleanup events in a timely manner. This in turn enables the list of queued cleanup events to grow infinitely large over time, allowing the configured `max-cache-size` limit to be significantly exceeded. This issue affects BIND 9 versions 9.16.0 through 9.16.45 and 9.16.8-S1 through 9.16.45-S1.

Allocation of Resources Without Limits or Throttling

BIND 9 DNS Parsing Complexity DoS (v9.0.0-9.19.19)
CVE-2023-4408 7.5 - High - February 13, 2024

The DNS message parsing code in `named` includes a section whose computational complexity is overly high. It does not cause problems for typical DNS traffic, but crafted queries and responses may cause excessive CPU load on the affected `named` instance by exploiting this flaw. This issue affects both authoritative servers and recursive resolvers. This issue affects BIND 9 versions 9.0.0 through 9.16.45, 9.18.0 through 9.18.21, 9.19.0 through 9.19.19, 9.9.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.

BIND9 Crash: assertion failure via nxdomain-redirect (v9.129.19)
CVE-2023-5517 7.5 - High - February 13, 2024

A flaw in query-handling code can cause `named` to exit prematurely with an assertion failure when: - `nxdomain-redirect <domain>;` is configured, and - the resolver receives a PTR query for an RFC 1918 address that would normally result in an authoritative NXDOMAIN response. This issue affects BIND 9 versions 9.12.0 through 9.16.45, 9.18.0 through 9.18.21, 9.19.0 through 9.19.19, 9.16.8-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.

assertion failure

BIND 9 named Crash via DNS64+serve-stale v9.16.129.19.19
CVE-2023-5679 7.5 - High - February 13, 2024

A bad interaction between DNS64 and serve-stale may cause `named` to crash with an assertion failure during recursive resolution, when both of these features are enabled. This issue affects BIND 9 versions 9.16.12 through 9.16.45, 9.18.0 through 9.18.21, 9.19.0 through 9.19.19, 9.16.12-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.

BIND 9 ECS Cache Clean Degradation (9.11.3-9.18.21)
CVE-2023-5680 5.3 - Medium - February 13, 2024

If a resolver cache has a very large number of ECS records stored for the same name, the process of cleaning the cache database node for this name can significantly impair query performance. This issue affects BIND 9 versions 9.11.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.

Stack Overflow via Recursive Packet Parsing in BIND 9 Control Channel
CVE-2023-3341 7.5 - High - September 20, 2023

The code that processes control channel messages sent to `named` calls certain functions recursively during packet parsing. Recursion depth is only limited by the maximum accepted packet size; depending on the environment, this may cause the packet-parsing code to run out of available stack memory, causing `named` to terminate unexpectedly. Since each incoming control channel message is fully parsed before its contents are authenticated, exploiting this flaw does not require the attacker to hold a valid RNDC key; only network access to the control channel's configured TCP port is necessary. This issue affects BIND 9 versions 9.2.0 through 9.16.43, 9.18.0 through 9.18.18, 9.19.0 through 9.19.16, 9.9.3-S1 through 9.16.43-S1, and 9.18.0-S1 through 9.18.18-S1.

Stack Exhaustion

BIND 9 9.18.018: DNSTLS Assertion Crash
CVE-2023-4236 7.5 - High - September 20, 2023

A flaw in the networking code handling DNS-over-TLS queries may cause `named` to terminate unexpectedly due to an assertion failure. This happens when internal data structures are incorrectly reused under significant DNS-over-TLS query load. This issue affects BIND 9 versions 9.18.0 through 9.18.18 and 9.18.11-S1 through 9.18.18-S1.

assertion failure

BIND 9 Cache Bypass Exploit (named) Allows max-cache-size Exceeded 9.119.19
CVE-2023-2828 7.5 - High - June 21, 2023

Every `named` instance configured to run as a recursive resolver maintains a cache database holding the responses to the queries it has recently sent to authoritative servers. The size limit for that cache database can be configured using the `max-cache-size` statement in the configuration file; it defaults to 90% of the total amount of memory available on the host. When the size of the cache reaches 7/8 of the configured limit, a cache-cleaning algorithm starts to remove expired and/or least-recently used RRsets from the cache, to keep memory use below the configured limit. It has been discovered that the effectiveness of the cache-cleaning algorithm used in `named` can be severely diminished by querying the resolver for specific RRsets in a certain order, effectively allowing the configured `max-cache-size` limit to be significantly exceeded. This issue affects BIND 9 versions 9.11.0 through 9.16.41, 9.18.0 through 9.18.15, 9.19.0 through 9.19.13, 9.11.3-S1 through 9.16.41-S1, and 9.18.11-S1 through 9.18.15-S1.

Allocation of Resources Without Limits or Throttling

BIND 9 named Resc Termination via Malformed NSEC (9.16.8S19.18.15S1)
CVE-2023-2829 7.5 - High - June 21, 2023

A `named` instance configured to run as a DNSSEC-validating recursive resolver with the Aggressive Use of DNSSEC-Validated Cache (RFC 8198) option (`synth-from-dnssec`) enabled can be remotely terminated using a zone with a malformed NSEC record. This issue affects BIND 9 versions 9.16.8-S1 through 9.16.41-S1 and 9.18.11-S1 through 9.18.15-S1.

BIND 9 named Stack Overflow via Recusive Client Quota Loop (9.16.339.16.41)
CVE-2023-2911 7.5 - High - June 21, 2023

If the `recursive-clients` quota is reached on a BIND 9 resolver configured with both `stale-answer-enable yes;` and `stale-answer-client-timeout 0;`, a sequence of serve-stale-related lookups could cause `named` to loop and terminate unexpectedly due to a stack overflow. This issue affects BIND 9 versions 9.16.33 through 9.16.41, 9.18.7 through 9.18.15, 9.16.33-S1 through 9.16.41-S1, and 9.18.11-S1 through 9.18.15-S1.

Memory Corruption

Stale-Answer Race in BIND 9 9.16.129.19.8 Causing Assertion Failure
CVE-2022-3924 7.5 - High - January 26, 2023

This issue can affect BIND 9 resolvers with `stale-answer-enable yes;` that also make use of the option `stale-answer-client-timeout`, configured with a value greater than zero. If the resolver receives many queries that require recursion, there will be a corresponding increase in the number of clients that are waiting for recursion to complete. If there are sufficient clients already waiting when a new client query is received so that it is necessary to SERVFAIL the longest waiting client (see BIND 9 ARM `recursive-clients` limit and soft quota), then it is possible for a race to occur between providing a stale answer to this older client and sending an early timeout SERVFAIL, which may cause an assertion failure. This issue affects BIND 9 versions 9.16.12 through 9.16.36, 9.18.0 through 9.18.10, 9.19.0 through 9.19.8, and 9.16.12-S1 through 9.16.36-S1.

assertion failure

BIND 9 Repeated Response ECS Assertion Failure (Fixed 9.11.38, 9.16.37)
CVE-2022-3488 7.5 - High - January 26, 2023

Processing of repeated responses to the same query, where both responses contain ECS pseudo-options, but where the first is broken in some way, can cause BIND to exit with an assertion failure. 'Broken' in this context is anything that would cause the resolver to reject the query response, such as a mismatch between query and answer name. This issue affects BIND 9 versions 9.11.4-S1 through 9.11.37-S1 and 9.16.8-S1 through 9.16.36-S1.

assertion failure

BIND 9.169.19 DoS via Flooding Dynamic DNS Updates
CVE-2022-3094 7.5 - High - January 26, 2023

Sending a flood of dynamic DNS updates may cause `named` to allocate large amounts of memory. This, in turn, may cause `named` to exit due to a lack of free memory. We are not aware of any cases where this has been exploited. Memory is allocated prior to the checking of access permissions (ACLs) and is retained during the processing of a dynamic update from a client whose access credentials are accepted. Memory allocated to clients that are not permitted to send updates is released immediately upon rejection. The scope of this vulnerability is limited therefore to trusted clients who are permitted to make dynamic zone changes. If a dynamic update is REFUSED, memory will be released again very quickly. Therefore it is only likely to be possible to degrade or stop `named` by sending a flood of unaccepted dynamic updates comparable in magnitude to a query flood intended to achieve the same detrimental outcome. BIND 9.11 and earlier branches are also affected, but through exhaustion of internal resources rather than memory constraints. This may reduce performance but should not be a significant problem for most servers. Therefore we don't intend to address this for BIND versions prior to BIND 9.16. This issue affects BIND 9 versions 9.16.0 through 9.16.36, 9.18.0 through 9.18.10, 9.19.0 through 9.19.8, and 9.16.8-S1 through 9.16.36-S1.

Dangling pointer

BIND 9 Resolver Crash with Stale Cache/Answer & RRSIG Query (9.16.12-9.19.8)
CVE-2022-3736 7.5 - High - January 26, 2023

BIND 9 resolver can crash when stale cache and stale answers are enabled, option `stale-answer-client-timeout` is set to a positive integer, and the resolver receives an RRSIG query. This issue affects BIND 9 versions 9.16.12 through 9.16.36, 9.18.0 through 9.18.10, 9.19.0 through 9.19.8, and 9.16.12-S1 through 9.16.36-S1.

BIND DNSSEC RRSIG Owner Name Validation Bypass
CVE-2022-3346 6.5 - Medium - December 28, 2022

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.

Insufficient Verification of Data Authenticity

Memory Leak via Malformed EdDSA in BIND DNS Resolver
CVE-2022-38178 7.5 - High - September 21, 2022

By spoofing the target resolver with responses that have a malformed EdDSA signature, an attacker can trigger a small memory leak. It is possible to gradually erode available memory to the point where named crashes for lack of resources.

Memory Leak

BIND named Crash via Resolver Query (CVE-2022-3080)
CVE-2022-3080 7.5 - High - September 21, 2022

By sending specific queries to the resolver, an attacker can cause named to crash.

Memory Leak in ISC BIND via Malformed ECDSA Signatures
CVE-2022-38177 7.5 - High - September 21, 2022

By spoofing the target resolver with responses that have a malformed ECDSA signature, an attacker can trigger a small memory leak. It is possible to gradually erode available memory to the point where named crashes for lack of resources.

Memory Leak

Buffer Overread CVE-2022-2881: Potential Info Disclosure or Crash
CVE-2022-2881 8.2 - High - September 21, 2022

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

Out-of-bounds Read

Memory Exhaustion DoS in Unknown Component
CVE-2022-2906 7.5 - High - September 21, 2022

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.

Memory Leak