PT-2026-63417 · Isc · Bind 9

CVE-2026-11721 · Published 2026-07-22 · Updated 2026-07-22

Mitre

CVSS v3.1

7.5

High

Base vector

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

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.

Fix

Weakness Enumeration

CWE-1284

Related Identifiers

CVE-2026-11721

Affected Products

Bind 9

References · 4

• https://kb.isc.org/docs/cve-2026-11721 · Vendor Advisory
• https://downloads.isc.org/isc/bind9/9.21.24 · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2026-11721 · Security Note
• https://downloads.isc.org/isc/bind9/9.20.26 · Patch