CVE-2018-5736: Multiple transfers of a zone in quick succession can cause an assertion failure in rbtdb.c
mcnally at isc.org
Fri May 18 22:29:57 UTC 2018
Document Version: 2.0
Posting date: 18 May 2018
Program Impacted: BIND
Versions affected: 9.12.0 and 9.12.1
Exploitable: Remotely, if an attacker can trigger a zone transfer
An error in zone database reference counting can lead to an
assertion failure if a server which is running an affected version
of BIND attempts several transfers of a slave zone in quick
This defect could be deliberately exercised by an attacker who
is permitted to cause a vulnerable server to initiate zone
transfers (for example: by sending valid NOTIFY messages), causing
the named process to exit after failing the assertion test.
Authoritative servers that serve slave zones are vulnerable to
potential denial of service if all of the following are true:
+ they are running an affected version of BIND (BIND 9.12.0
+ at least one of the zones for which they are providing service
is of type "slave"
+ they permit NOTIFY messages from any source.
CVSS Score: 5.3
CVSS Vector: CVSS:3.0/AV:N/AC:H/PR:L/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:
For servers which must receive notifies to keep slave zone
contents current, no complete workarounds are known although
restricting BIND to only accept NOTIFY messages from authorized
sources can greatly mitigate the risk of attack.
No known active exploits.
The reference counting error which can be exploited in this
vulnerability is present in only two public release versions of
BIND, 9.12.0 and 9.12.1. If you are running an affected version
then upgrade to BIND 9.12.1-P1
ISC would like to thank SWITCH for informing us of this vulnerability.
Document Revision History:
1.0 Advance Notification 09 May 2018
2.0 Public Disclosure 18 May 2018
See our BIND9 Security Vulnerability Matrix at
https://kb.isc.org/article/AA-00913 for a complete listing of
Security Vulnerabilities and versions affected.
Do you still have questions? Questions regarding this advisory
should go to security-officer at isc.org. To report a new issue,
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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
ISC Security Vulnerability Disclosure Policy:
Details of our current security advisory policy and practice can
be found here: https://kb.isc.org/article/AA-00861
This Knowledge Base article https://kb.isc.org/article/AA-01602 is
the complete and official security advisory document.
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