CVE-2016-8864: A problem handling responses containing a DNAME answer can lead to an assertion failure
Document version: 2.0
Posting date: 1 November 2016
Program impacted: BIND
Versions affected: 9.0.x -> 9.8.x, 9.9.0 -> 9.9.9-P3, 9.9.3-S1 -> 9.9.9-S5, 9.10.0 -> 9.10.4-P3, 9.11.0
A defect in BIND 9's handling of responses containing a DNAME answer can cause a resolver to exit after encountering an assertion failure in
During processing of a recursive response that contains a DNAME record in the answer section, BIND can stop execution after encountering an assertion error in
resolver.c (error message: "INSIST((valoptions & 0x0002U) != 0) failed") or
db.c (error message: "REQUIRE(targetp != ((void *)0) && *targetp == ((void *)0)) failed").
A server encountering either of these error conditions will stop, resulting in denial of service to clients. The risk to authoritative servers is minimal; recursive servers are chiefly at risk.
CVSSv3 Score: 7.5
CVSSv3 Vector: CVSS:3.0/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://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Workarounds: None known.
No known active exploits, but a query which could trigger the crash was briefly discussed on a public mailing list before the domain owner pulled the record causing the problem.
Solution: Upgrade to the patched release most closely related to your current version of BIND. These can all be downloaded from https://www.isc.org/downloads.
- BIND 9 version 9.9.9-P4
- BIND 9 version 9.10.4-P4
- BIND 9 version 9.11.0-P1
BIND 9 Supported Preview edition is a feature preview version of BIND provided exclusively to eligible ISC Support customers.
- BIND 9 version 9.9.9-S6
Acknowledgements: ISC would like to thank Tony Finch (University of Cambridge), Marco Davids (SIDN Labs), and others for reporting and extending our understanding of the issue.
Document Revision History:
1.0 Advance Notification, 21 October 2016
1.1 Updated versions affected; Updated Acknowledgements, 27 October 2016
2.0 Public Announcement, 1 November 2016
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/downloads/).
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