CVE-2026-77119

Medium

Description

A validly signed NSEC3 from an unrelated sibling zone may be accepted as an insecurity proof, downgrading a secure delegation and letting a forged unsigned answer through. This issue affects BIND 9 versions 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.

SeverityMedium

CVSS5.9

Exploit probability—

ProductBIND 9

PublishedSep 16, 2026

First seenSep 16, 2026

Weakness typeCWE-346CWE-346

How to fix

Patches

Vendor advisories

kb.isc.org/docs/cve-2026-77119

Affected products

Product	Affected versions	Fixed in
ISC BIND 9	9.11.0 ≤ v ≤ 9.18.50, 9.20.0 ≤ v ≤ 9.20.27, 9.21.0 ≤ v ≤ 9.21.25, 9.11.3-S1 ≤ v ≤ 9.18.50-S1, 9.20.9-S1 ≤ v ≤ 9.20.27-S1	—

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