A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the `max-cache-size` parameter.
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.

Project Subscriptions

Vendors Products
Advisories
Source ID Title
Debian DSA Debian DSA DSA-6395-1 bind9 security update
Fixes

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.


Workaround

No workarounds known.

History

Thu, 23 Jul 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-400
References
Metrics threat_severity

None

threat_severity

Important


Wed, 22 Jul 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 22 Jul 2026 15:00:00 +0000

Type Values Removed Values Added
Description A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the `max-cache-size` parameter. 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.
Title Potential memory usage beyond configured limits
First Time appeared Isc
Isc bind
Weaknesses CWE-770
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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: isc

Published:

Updated: 2026-07-22T18:53:14.635Z

Reserved: 2026-06-08T20:17:01.626Z

Link: CVE-2026-11622

cve-icon Vulnrichment

Updated: 2026-07-22T18:53:10.652Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-22T00:00:00Z

Links: CVE-2026-11622 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-23T18:45:03Z

Weaknesses