CVE-2026-13321

HIGH 8.6

DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field

CVSS Score

8.6

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-346
Vendor	isc
Product	bind 9
Published	Jul 22, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

ISC / BIND 9

9.11.0 ≤ 9.18.50 9.20.0 ≤ 9.20.24 9.21.0 ≤ 9.21.23 9.11.3-S1 ≤ 9.18.50-S1 9.20.9-S1 ≤ 9.20.24-S1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

ISC would like to thank Qifan Zhang of Palo Alto Networks for bringing this vulnerability to our attention.