CVE-2026-13321 PUBLISHED

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

Assigner: isc
Reserved: 25.06.2026 Published: 22.07.2026 Updated: 22.07.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
CVSS Score: 8.6

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	High
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	ISC
Product	BIND 9
Versions	Default: unaffected affected from 9.11.0 to 9.18.50 (incl.) affected from 9.20.0 to 9.20.24 (incl.) affected from 9.21.0 to 9.21.23 (incl.) affected from 9.11.3-S1 to 9.18.50-S1 (incl.) affected from 9.20.9-S1 to 9.20.24-S1 (incl.)

Exploits

We are not aware of any active exploits.

Workarounds

No workarounds known.

Solutions

Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.26, 9.21.24, or 9.20.26-S1.

Credits

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

References

Problem Types

CWE-346 Origin Validation Error CWE

Impacts

An attacker controlling any DNSSEC-signed zone can craft NSEC records that span into victim zones, enabling cross-zone cache poisoning with authenticated denial-of-service responses (AD=1).