REDHAT-BUG-2451305: High severity ISC BIND 9 vulnerability

Published Mar 25, 2026
·
Updated

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.

Affected Software

1 affected component
ISC BIND 9>=9.11.0<=9.16.50, >=9.18.0<=9.18.46, >=9.20.0<=9.20.20, >=9.21.0<=9.21.19, >=9.11.3-S1<=9.16.50-S1, >=9.18.11-S1<=9.18.46-S1, >=9.20.9-S1<=9.20.20-S1

Event History

Mar 25, 2026
Data Sourced
via Red Hat·02:02 PM
DescriptionSeverityAffected Software
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Frequently Asked Questions

1

What is the severity of REDHAT-BUG-2451305?

The severity of REDHAT-BUG-2451305 is classified as moderate due to potential CPU exhaustion from maliciously crafted DNS zones.

2

How do I fix REDHAT-BUG-2451305?

To fix REDHAT-BUG-2451305, upgrade to a patched version of ISC BIND 9 that is not affected by this vulnerability.

3

Which versions of ISC BIND 9 are affected by REDHAT-BUG-2451305?

REDHAT-BUG-2451305 affects ISC BIND 9 versions from 9.11.0 to 9.16.50 and multiple others within specific ranges.

4

What is the impact of REDHAT-BUG-2451305 on DNS resolvers?

The impact of REDHAT-BUG-2451305 on DNS resolvers is excessive CPU consumption when processing malicious DNSSEC validation requests.

5

Are authoritative-only servers affected by REDHAT-BUG-2451305?

Authoritative-only servers are generally unaffected but may still be vulnerable in certain circumstances that involve recursive queries.

Contact

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