CVE-2026-11605

Unnecessary validation of DNSSEC signed records

Published Jul 22, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

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
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
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-400
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

threat_severity

Important

Type Values Removed Values Added
First Time appeared Isc bind 9
Vendors & Products Isc bind 9
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 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.
Title Unnecessary validation of DNSSEC signed records
First Time appeared Isc
Isc bind
Weaknesses CWE-408
CPEs cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
Vendors & Products Isc
Isc bind
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
isc
Published
Updated
Jul 22, 2026, 6:53 PM
Reserved
Jun 8, 2026, 3:26 PM
Status
Analyzed
Published
Jul 22, 2026, 3:16 PM
Modified
Nov 2, 2026, 5:44 PM
Severity
Important
Public date
Jul 22, 2026, 12:00 AM