CVE-2023-2829: Malformed NSEC records can cause named to terminate unexpectedly when synth-from-dnssec is enabled
Document version: 2.0
Posting date: 21 June 2023
Program impacted: BIND 9
BIND Supported Preview Edition
- 9.16.8-S1 -> 9.16.41-S1
- 9.18.11-S1 -> 9.18.15-S1
named instance configured to run as a DNSSEC-validating recursive resolver with the Aggressive Use of DNSSEC-Validated Cache (RFC 8198) option (
synth-from-dnssec) enabled can be remotely terminated using a zone with a malformed NSEC record.
By sending specific queries to the resolver, an attacker can cause
named to terminate unexpectedly.
Note that the BIND configuration option
synth-from-dnssec is enabled by default in all versions of BIND 9.18 and 9.18-S and newer. In earlier versions of BIND that had this option available, it was disabled unless activated explicitly in
CVSS Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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:N/S:U/C:N/I:N/A:H&version=3.1.
no prevents the problem.
We are not aware of any active exploits.
Upgrade to the patched release most closely related to your current version of BIND 9:
BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.
ISC would like to thank Greg Kuechle from SaskTel for bringing this vulnerability to our attention.
Document revision history:
- 1.0 Early Notification, 14 June 2023
- 2.0 Public disclosure, 21 June 2023
See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected.
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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-2023-2829 is the complete and official security advisory document.
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