CVE: CVE-2022-0396
Document version: 2.0
Posting date: 16 March 2022
Program impacted: BIND
Versions affected: BIND 9.16.11 -> 9.16.26, 9.17.0 -> 9.18.0 and versions
                    9.16.11-S1 -> 9.16.26-S1 of the BIND Supported Preview
Severity: Medium
Exploitable: Remotely


ISC recently discovered an issue in BIND that allows TCP connection slots
   to be consumed for an indefinite time frame via a specifically crafted
   TCP stream sent from a client. This issue is present in BIND 9.16.11 to
   9.16.26 (including S editions), and 9.18.0.

   This issue can only be triggered on BIND servers which have
   `keep-response-order` enabled, which is not the default configuration.
   The `keep-response-order` option is an ACL block; any hosts which are
   specified within it will be able to trigger this issue on affected


   Specifically crafted TCP streams can cause connections to BIND to remain
   in CLOSE_WAIT status for an indefinite period of time, even after the
   client has terminated the connection.

CVSS Score: 4.9


For more information on the Common Vulnerability Scoring System and to
obtain your specific environmental score please visit:


   To mitigate this issue in all affected versions of BIND, use the default
   setting of:

     keep-response-order { none; }.

Active exploits:

   We are not aware of any active exploits.


   Upgrade to the patched release most closely related to your current
   version of BIND:


   BIND Supported Preview Edition is a special feature-preview branch of
   BIND provided to eligible ISC support customers.


Document revision history:

   1.0 Early Notification, 9 March 2022
   1.1 Grammatical edit to Description, 16 March 2022
   2.0 Public disclosure, 16 March 2022

Related documents:

See "CVE-2019-6477: TCP-pipelined queries can bypass tcp-clients limit" for
more information regarding CVE-2019-6477, in which ISC recommended setting
`keep-response-order` to `any` to work around a previous issue where BIND
was not respecting the TCP client limit:

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 go
to To report a new issue, please encrypt your
message using's PGP key which can be found here: If you are unable to use encrypted email, you
may also report new issues at:


ISC patches only currently supported versions. When possible we indicate
EOL versions affected. (For current information on which versions are
actively supported, please see

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

The Knowledgebase article 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.

bind-announce mailing list

Reply via email to