CVE: CVE-2026-10822
Title: Key Record using PRIVATEDNS algorithm may lead to unexpected exit
Document version: 2.0
Posting date: 22 July 2026
Program impacted: BIND 9
Versions affected:
BIND
- 9.18.0 -> 9.18.50
- 9.20.0 -> 9.20.24
- 9.21.0 -> 9.21.23
BIND Supported Preview Edition
- 9.18.11-S1 -> 9.18.50-S1
- 9.20.9-S1 -> 9.20.24-S1
Severity: Medium
Exploitable: Remotely
Description:
If BIND encounters a particular invalid data structure in a DNS record, it will accept the invalid data, and may subsequently abort and exit.
BIND will first need to store a DNS record for a key (KEY, DNSKEY, etc.). That key must specify a PRIVATEDNS algorithm (253), and in the algorithm identifier, improperly give a length longer than the actual identifier data. The invalid identifier will be stored. If BIND later needs to render that record to text, it will use the invalid length during processing, leading to a consistency check failing.
Impact:
9.20 and 9.21 may abort and exit unexpectedly.
9.18 has not actually been confirmed to exhibit the unexpected exit but does share the problem code.
CVSS Score: 6.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H&version=3.1.
Workarounds:
No workarounds known.
Active exploits:
This flaw was discovered in internal testing. We are not aware of any active exploits.
Solution:
Upgrade to the patched release most closely related to your current version of BIND 9:
- 9.20.26
- 9.21.24
BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.
- 9.20.26-S1
Document revision history:
- 1.0 Early Notification, 15 July 2026
- 1.1 Revised the list of fixed versions, 20 July 2026
- 2.0 Public disclosure, 22 July 2026
Related documents:
See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected.
Do you still have questions?
Questions regarding this advisory should be posted as confidential GitLab issues at:
https://gitlab.isc.org/isc-projects/bind9/-/issues/new?issue[confidential]=true
Note:
ISC patches only currently supported versions. When possible we indicate EOL versions affected. For current information on which versions are actively supported, please see https://www.isc.org/download/.
ISC Security Vulnerability Disclosure Policy:
Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy at https://kb.isc.org/docs/aa-00861.
The Knowledgebase article https://kb.isc.org/docs/cve-2026-10822 is the complete and official security advisory document.
Legal Disclaimer:
Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time. A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors.