CVE-2026-11605

Unnecessary validation of DNSSEC signed records

State: Published
Severity: 7.5 High
Published: Jul 22, 2026
Updated: Jul 22, 2026
Reserved: Jun 8, 2026

Description

The issue is a resource exhaustion vulnerability associated with DNSSEC validation. BIND always validates all RRSIG records in an answer, even if they are not strictly needed. A query to an authoritative server/zone which returns many valid but superfluous RRSIG records causes the validator to waste disproportionate CPU time. This issue affects BIND 9 versions 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, and 9.20.9-S1 through 9.20.24-S1.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	isc

Weaknesses

CWE-408 Incorrect Behavior Order - Early Amplification

Affected Products

Product	Versions
BIND 9ISC	9.20.0 through 9.20.24Affected 9.21.0 through 9.21.23Affected 9.20.9-S1 through 9.20.24-S1Affected

References

CVE-2026-11605vendor-advisory
https://downloads.isc.org/isc/bind9/9.20.26patch
https://downloads.isc.org/isc/bind9/9.21.24patch

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