CVE-2022-3736: named configured to answer from stale cache may terminate unexpectedly while processing RRSIG queries
  • 25 Jan 2023
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CVE-2022-3736: named configured to answer from stale cache may terminate unexpectedly while processing RRSIG queries

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Article summary

CVE: CVE-2022-3736

Document version: 2.0

Posting date: 25 January 2023

Program impacted: BIND 9

Versions affected:


  • 9.16.12 -> 9.16.36
  • 9.18.0 -> 9.18.10
  • 9.19.0 -> 9.19.8

BIND Supported Preview Edition

  • 9.16.12-S1 -> 9.16.36-S1

(The flaw exists in the implementation of the stale-answer-client-timeout option, which was first effectively introduced in BIND 9.16.12 and BIND 9.16.12-S1. That option is also configurable in BIND 9.11.33-S1 and newer BIND 9.11-S versions, but it is always replaced with 0 in all BIND 9.11.x-S1 releases.)

Severity: High

Exploitable: Remotely


BIND 9 resolver can crash when stale cache and stale answers are enabled, option stale-answer-client-timeout is set to a positive integer, and the resolver receives an RRSIG query.


By sending specific queries to the resolver, an attacker can cause named to crash.

CVSS Score: 7.5


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


Setting stale-answer-client-timeout to 0 or to off/disabled will prevent BIND from crashing due to this issue.

Active exploits:

We are not aware of any active exploits.


Upgrade to the patched release most closely related to your current version of BIND 9:

  • 9.16.37
  • 9.18.11
  • 9.19.9

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

  • 9.16.37-S1


ISC would like to thank Borja Marcos from Sarenet (with assistance by Iratxe Niño from Fundación Sarenet) for bringing this vulnerability to our attention.

Document revision history:

  • 1.0 Early Notification, 18 January 2023
  • 2.0 Public disclosure, 25 January 2023

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 mailed 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.

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