CVE-2026-13321: DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-22 · updated 2026-10-24
Weakness: CWE-346

Description

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.

Affected products

ISC BIND: from 9.11.0 through 9.18.50; from 9.20.0 through 9.20.24; from 9.21.0 through 9.21.23; from 9.11.3-S1 through 9.18.50-S1; from 9.20.9-S1 through 9.20.24-S1

References

https://downloads.isc.org/isc/bind9/9.20.26
https://downloads.isc.org/isc/bind9/9.21.24
https://kb.isc.org/docs/cve-2026-13321

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