CVE-2026-19630

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Denial of Service in BIND Resolver

Publication date: 2026-10-21

Last updated on: 2026-10-26

Assigner: Internet Systems Consortium (ISC)

Description

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. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.

CVSS Scores

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Meta Information

Published

2026-10-21

Last Modified

2026-10-26

Generated

2026-11-10

AI Q&A

2026-10-22

EPSS Evaluated

2026-11-09

NVD

CVE-2026-19630

EUVD

EUVD-2026-107252

Affected Vendors & Products

Vendor	Product	Version / Range
ISC	BIND 9	9.11.0
ISC	BIND 9	9.20.0
ISC	BIND 9	9.21.0
ISC	BIND 9	9.11.3-S1
ISC	BIND 9	9.20.9-S1

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-407	An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

Attack-Flow Graph

Executive Summary

CVE-2026-19630 is a vulnerability in BIND 9 DNS resolver software where maliciously crafted DNS messages with a specific structure cause BIND to consume excessive CPU and memory without limits. This leads to resource exhaustion and potential denial-of-service conditions.

Detection Guidance

This vulnerability is detected by checking the BIND version running on your system. Use the command 'named -v' or 'rndc -v' to check the installed version. If it falls within the affected ranges (9.11.0-9.18.50, 9.20.0-9.20.29, 9.21.0-9.21.26, or their Supported Preview Editions), the system is vulnerable.

Impact Analysis

This vulnerability can cause your DNS resolver to become unresponsive or crash due to high CPU and memory usage. It may disrupt network services relying on DNS resolution, leading to downtime for websites or applications.

Compliance Impact

This vulnerability can lead to denial-of-service conditions by exhausting system resources, which may disrupt critical services. For GDPR, this could impact availability of personal data processing systems, potentially violating Article 32 requirements for resilience. For HIPAA, it may affect the availability of systems handling protected health information, risking compliance with Security Rule requirements for access and integrity.

Mitigation Strategies

Upgrade to a patched version of BIND immediately. For standard versions, upgrade to BIND 9.20.30 or 9.21.27. For Supported Preview Editions, upgrade to 9.20.30-S1. Download the latest versions from ISC's official site (e.g., https://downloads.isc.org/isc/bind9/9.20.30 or https://downloads.isc.org/isc/bind9/9.21.27).

After upgrading, restart the BIND service using 'systemctl restart named' or the equivalent command for your system.

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