CVE-2026-11721 | It is possible for an attacker's zone to respond to a query … | CVSS 7.5 HIGH

Description

It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). 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.

Metadata

CVE ID: CVE-2026-11721
State: PUBLISHED
Assigner: isc
Reserved: 2026-06-09 01:19 UTC
Published: 2026-07-22 14:13 UTC
Last updated: 2026-07-22 14:13 UTC
Primary CWE: CWE-1284
CWE-1284 Improper Validation of Specified Quantity in Input
Vendor / Product: ISC / BIND 9
Sources: cve.org · NVD

Severity & Metrics

7.5 HIGH CVSS 3.1

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

Affected products (1)

Vendor	Product	Platform	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 …

Weakness (CWE)

CWE	Source	Description
CWE-1284	cna	CWE-1284 Improper Validation of Specified Quantity in Input

CVSS scores (1)

Score	Severity	Version	Source	Vector
7.5	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References (3)