CVE-2026-13321

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

Published Jul 22, 2026 CVSS 3.1 · 8.6 High EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

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.


Vendor Workaround

No workarounds known.

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DLA Debian DLA DLA-4725-1 bind9 security update
Debian DSA Debian DSA DSA-6395-1 bind9 security update
Ubuntu USN Ubuntu USN USN-8648-1 Bind vulnerabilities
Ubuntu USN Ubuntu USN USN-8929-1 Bind vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
cpe:2.3:a:isc:bind:*:*:*:*:supported_preview:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field
First Time appeared Isc
Isc bind
Weaknesses CWE-346
CPEs cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
Vendors & Products Isc
Isc bind
References
Metrics cvssV3_1

{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
isc
Published
Updated
Jul 22, 2026, 6:51 PM
Reserved
Jun 25, 2026, 8:45 AM
Status
Analyzed
Published
Jul 22, 2026, 3:16 PM
Modified
Nov 2, 2026, 5:51 PM
Severity
Important
Public date
Jul 22, 2026, 12:00 AM