CVE-2017-3136: An error handling synthesized records could cause an assertion failure when using DNS64 with "break-dnssec yes;"
Document version: 2.0
Posting date: 12 April 2017
Program impacted: BIND
Versions affected: 9.8.0 -> 9.8.8-P1, 9.9.0 -> 9.9.9-P6, 9.9.10b1->9.9.10rc1, 9.10.0 -> 9.10.4-P6, 9.10.5b1->9.10.5rc1, 9.11.0 -> 9.11.0-P3, 9.11.1b1->9.11.1rc1, 9.9.3-S1 -> 9.9.9-S8
Severity: Medium, but only a risk to systems with specific configurations
A query with a specific set of characteristics could cause a server using DNS64 to encounter an assertion failure and terminate.
An attacker could deliberately construct a query enabling denial-of-service against a server, if it was configured to use the DNS64 feature and other preconditions were met.
Servers are at risk if they are configured to use DNS64 and if the option "break-dnssec yes;" is in use.
CVSS Score: 5.9
CVSS Vector: CVSS:3.0/AV:N/AC:H/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://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
Servers which have configurations which require DNS64 and "break-dnssec yes;" should upgrade. Servers which are not using these features in conjunction are not at risk from this defect.
Active exploits: No known active exploits.
Solution: Upgrade to the patched release most closely related to your current version of BIND. These can all be downloaded from http://www.isc.org/downloads.
- BIND 9 version 9.9.9-P8
- BIND 9 version 9.10.4-P8
- BIND 9 version 9.11.0-P5
BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.
- BIND 9 version 9.9.9-S10
New maintenance releases of BIND are also scheduled which contain the fix for this vulnerability. In addition to the security releases listed above, fixes for this vulnerability are also included in these release candidate versions:
- BIND 9 version 9.9.10rc3
- BIND 9 version 9.10.5rc3
- BIND 9 version 9.11.1rc3
Acknowledgements: ISC would like to thank Oleg Gorokhov of Yandex for making us aware of this vulnerability.
Document Revision History:
1.0 Advance Notification, 08 March 2017
1.1 Revised Publication Date; Added pre-releases to Versions Affected, 20 March 2017
2.0 Public Announcement, 12 April 2017
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 email@example.com. To report a new issue, please encrypt your message using firstname.lastname@example.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/. If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/.
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/downloads/).
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