CVE-2026-1519: Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

Published Mar 25, 2026
·
Updated

Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

Other sources

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:

— IBM

Affected Software

9 affected componentsFixes available
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
Microsoft azl3 bind 9.20.18-1
Patch available
IBM QRadar<=7.5.0 - 7.5.0 UP15 IF02
ISC BIND>=9.11.0<=9.16.50
ISC BIND>=9.18.0<9.18.47
ISC BIND>=9.20.0<9.20.21
ISC BIND>=9.21.0<9.21.20
Microsoft cbl2 bind 9.16.50-3<9.16.50-4
9.16.50-4
Microsoft azl3 bind 9.20.18-1<9.20.21-1
9.20.21-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 9.16.50-4
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 9.20.21-1
  3. Upgrade

    Upgrade BIND 9 to a version that resolves this vulnerability.

    Fixed in 9.18.47
  4. Upgrade

    Upgrade BIND 9 to a version that resolves this vulnerability.

    Fixed in 9.20.21
  5. Upgrade

    Upgrade BIND 9 to a version that resolves this vulnerability.

    Fixed in 9.21.20
  6. Upgrade

    Upgrade BIND 9 to a version that resolves this vulnerability.

    Fixed in 9.18.47-S1
  7. Upgrade

    Upgrade BIND 9 to a version that resolves this vulnerability.

    Fixed in 9.20.21-S1

Event History

Mar 25, 2026
CVE Published
via MITRE·01:25 PM
Data Sourced
via MITRE·01:25 PM
RemedyDescriptionSeverityWeakness
Data Sourced
via Red Hat·02:02 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
RemedyDescriptionSeverityWeaknessAffected Software
Mar 29, 2026
Data Sourced
via Microsoft·08:01 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:01 AM
DescriptionSeverityWeakness
Updated
via Microsoft·08:01 AM
DescriptionSeverity
May 25, 2026
Data Sourced
via IBM·12:00 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

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Frequently Asked Questions

1

What is the severity of CVE-2026-1519?

CVE-2026-1519 is rated as high severity due to the potential for excessive CPU load during DNSSEC validation.

2

How do I fix CVE-2026-1519?

To mitigate CVE-2026-1519, upgrade to the latest version of BIND that addresses this vulnerability.

3

What versions of BIND are affected by CVE-2026-1519?

CVE-2026-1519 affects BIND versions from 9.11.0 to 9.16.50 and from 9.18.0 to 9.18.46, among others.

4

What type of servers are vulnerable to CVE-2026-1519?

BIND resolvers performing DNSSEC validation are vulnerable to CVE-2026-1519, while authoritative-only servers are generally unaffected.

5

What issue does CVE-2026-1519 highlight?

CVE-2026-1519 highlights a problem where excessive NSEC3 iterations can lead to high CPU load during insecure delegation validation.

Company

Resources

Contact

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