Knowledge Base ISC Main Website Ask a Question/Contact ISC
CVE-2017-3138: named exits with a REQUIRE assertion failure if it receives a null command string on its control channel
Author: Michael McNally Reference Number: AA-01471 Views: 123797 Created: 2017-04-12 17:30 Last Updated: 2017-04-12 23:35 0 Rating/ Voters

Document Version: 
Posting date: 
12 April 2017
Program Impacted: 
Versions affected: 
9.9.9->9.9.9-P7, 9.9.10b1->9.9.10rc2, 9.10.4->9.10.4-P7, 9.10.5b1->9.10.5rc2, 9.11.0->9.11.0-P4, 9.11.1b1->9.11.1rc2, 9.9.9-S1->9.9.9-S9
Remotely, from hosts that are within the ACL permitted access to the control channel


named contains a feature which allows operators to issue commands to a running server by communicating with the server process over a control channel, using a utility program such as rndc.

A regression introduced in a recent feature change has created a situation under which some versions of named can be caused to exit with a REQUIRE assertion failure if they are sent a null command string.


The BIND control channel is not configured by default, but when configured will accept commands from those IP addresses that are specified in its access control list and/or from clients which present the proper transaction key.  Using this defect, an attacker can cause a running server to stop if they can get it to accept control channel input from them.  In most instances this is not as bad as it sounds, because existing commands permitted over the control channel (i.e. "rndc stop") can already be given to cause the server to stop.

However, BIND 9.11.0 introduced a new option to allow "read only" commands over the command channel.  Using this restriction, a server can be configured to limit specified clients to giving control channel commands which return information only (e.g. "rndc status") without affecting the operational state of the server.  The defect described in this advisory, however, is not properly stopped by the "read only" restriction, in essence permitting a privilege escalation allowing a client which should only be permitted the limited set of "read only" operations to cause the server to stop execution.

CVSS Score:  6.5

CVSS Vector:  CVSS:3.0/AV:N/AC:L/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:


None.  However, in a properly configured server, access to the control channel should already be limited by either network ACLs, TSIG keys, or both.

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

  • 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 Mike Lalumiere of Dyn, Inc., for bringing this issue to our attention.

Document Revision History:

1.0 Advance Notification 20 March 2017
1.1 Revised Acknowledgements and Versions Affected 22 March 2017
1.2 Added mention of maintenance releases to the Solution section 31 March 2017
2.0 Public Announcement 12 April 2017

Related Documents:

See our BIND9 Security Vulnerability Matrix at for a complete listing of Security Vulnerabilities and versions affected.

If you'd like more information on ISC Subscription Support and Advance Security Notifications, please visit

Do you still have questions?  Questions regarding this advisory should go to security-officer@isc.orgTo report a new issue, please encrypt your message using's PGP key which can be found here:  If you are unable to use encrypted email, you may also report new issues at:

Note: 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:

This Knowledge Base article is the complete and official security advisory document.

Legal Disclaimer:

Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time.  A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors.

© 2001-2018 Internet Systems Consortium

For assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership.

ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website.

  • There is no feedback for this article
Quick Jump Menu