CVE-2016-2088: A response containing multiple DNS cookies causes servers with cookie support enabled to exit with an assertion failure.
mcnally at isc.org
Wed Mar 9 21:05:57 UTC 2016
Document Version: 2.0
Posting date: 09 March 2016
Program Impacted: BIND
Versions affected: 9.10.0 -> 9.10.3-P3
BIND 9.10 has preliminary support for DNS cookies (or source
identity tokens), a proposed mechanism designed to allow lightweight
transaction security between a querying party and a nameserver.
An error in the BIND code implementing support for this optional
feature permits a deliberately misconstructed packet containing
multiple cookie options to cause named to terminate with an
INSIST assertion failure in resolver.c if DNS cookie support is
enabled in the server. Only servers with DNS cookie support
enabled at build time can be affected by this defect; in servers
which do not have DNS cookie support selected any cookies
encountered will be ignored as unknown option types.
Servers which are built with DNS cookie support enabled are
vulnerable to denial of service if an attacker can cause them
to receive and process a response that contains multiple cookie
CVSS Score: 7.8
CVSS Vector: (AV:N/AC:L/Au:N/C:N/I:N/A:C)
For more information on the Common Vulnerability Scoring System and
to obtain your specific environmental score please visit:
Servers which do not have cookie support included are not at
risk from this vulnerability.
When BIND 9.10 is built from ISC-supported source, cookie support
is not selected by default. In order to be included it must be
elected using the "--enable-sit" command-line argument when
running the "configure" script in the top level source directory.
Operators with affected servers can re-configure and re-build
BIND without cookie support if they prefer not to upgrade to a
release containing the fix. However, ISC-provided binary packages
for Windows do have "--enable-sit" selected. Server operators
using the Windows binary packages should upgrade to the corrected
No known active exploits.
Re-configure and re-build BIND without enabling cookie support
or upgrade to the patched release most closely related to your
current version of BIND.
- BIND 9 version 9.10.3-P4
Document Revision History:
1.0 Advance Notification 02 March 2016
2.0 Public Disclosure. 09 March 2016
See our BIND9 Security Vulnerability Matrix at
https://kb.isc.org/article/AA-00913 for a complete listing of
Security Vulnerabilities and versions affected.
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be found here: https://kb.isc.org/article/AA-00861
This Knowledge Base article https://kb.isc.org/article/AA-01351 is
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