CVE-2026-19941Network attack vector

DNS cache poisoning via out-of-zone NSEC acceptance

Published Sep 16, 2026 · Updated Sep 16, 2026

DNSSEC validation bypass in BIND 9 allows remote attackers to poison resolver caches with an inapplicable NSEC record. named's checkwildcard() accepts an out-of-zone NSEC as proof that no wildcard exists, causing valid wildcard mappings to be cached as nonexistent. Exploitation requires control at the same or an upstream zone level; affected releases are 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

CVSS severity5.9
Medium
EPSS probabilityUnavailable
No score available in this record
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DNSSEC validation bypass in BIND 9 allows remote attackers to poison resolver caches with an inapplicable NSEC record. named's checkwildcard() accepts an out-of-zone NSEC as proof that no wildcard exists, causing valid wildcard mappings to be cached as nonexistent. Exploitation requires control at the same or an upstream zone level; affected releases are 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

The record

CVE
CVE-2026-19941
Published
Sep 16, 2026
Updated
Sep 16, 2026
Vendor
Internet Systems Consortium
Product
BIND 9
Classifications
T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=9.11.0 <=9.18.50
  2. Affected versionversion=9.11.3-S1 <=9.18.50-S1
  3. Affected versionversion=9.20.0 <=9.20.27
  4. Affected versionversion=9.20.9-S1 <=9.20.27-S1
  5. Affected versionversion=9.21.0 <=9.21.25

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Internet Systems Consortium · BIND 9version=9.11.0 <=9.18.50; version=9.11.3-S1 <=9.18.50-S1; version=9.20.0 <=9.20.27; version=9.20.9-S1 <=9.20.27-S1; version=9.21.0 <=9.21.25

Published CVSS scores

5.9Internet Systems ConsortiumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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