CVE-2022-0667: Assertion failure on delayed DS lookup
  • 25 Mar 2022
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CVE-2022-0667: Assertion failure on delayed DS lookup

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Article summary

CVE: CVE-2022-0667

Document version: 2.0

Posting date: 16 March 2022

Program impacted: BIND

Versions affected: BIND 9.18.0

Severity: High

Exploitable: Remotely


In BIND 9.18.0 the recursive client code was refactored. This refactoring introduced a "backstop lifetime timer".

While BIND is processing a request for a DS record that needs to be forwarded, it waits until this processing is complete or until the backstop lifetime timer has timed out. When the resume_dslookup() function is called as a result of such a timeout, the function does not test whether the fetch has previously been shut down. This introduces the possibility of triggering an assertion failure, which could cause the BIND process to terminate.

Only the BIND 9.18 branch is affected.


When the vulnerability is triggered the BIND process will exit.

CVSS Score: 7.0


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


No workarounds known.

Active exploits:

We are not aware of any active exploits.


  • Users of BIND 9.18.0 should upgrade to BIND 9.18.1

Document revision history:

1.0 Early Notification, 9 March 2022
2.0 Public disclosure, 16 March 2022

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 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

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Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy at

This Knowledgebase article is the complete and official security advisory document.

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