CVE-2011-4539: DHCP Regular Expressions Segfault
| Author: Sue Graves Reference Number: AA-00569 Views: 4218 Created: 2011-12-08 22:08 Last Updated: 2012-06-08 14:33
0 Rating/ Voters
DHCP Regular Expressions Segfault
Segmentation fault from dhcpd while processing an evaluated regular expression
Posting date: 07 Dec 2011
Versions affected: 4.0.x and higher, including all EOL versions back to 4.0, 4.1-ESV, and 4.2.x
A bug exists which allows an attacker who is able
to send DHCP Request packets, either directly or through a relay, to
remotely crash an ISC DHCP server if that server is configured to
evaluate expressions using a regular expression (i.e. uses the "~=" or
"~~" comparison operators.)
Further details are being withheld to allow administrators of
affected systems time to patch. You are potentially vulnerable if you
use regular expression comparison operators in your dhcpd.conf.
CVSS Score: 6.1
CVSS Equation: AV:
For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit:
This bug cannot be triggered if you are not using regular expressions in your configuration file.
Active exploits: None known at this time.
Solution: Upgrade to 4.1-ESV-R4 or 4.2.3-P1
Thank you to BlueCat Networks for finding and testing the issue.
Document Revision History
1.0 30 November 2011 - Phase I notified
1.1 6 December 2011 - Phase II & III notified
1.2 7 December 2011 - Public Release
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lack important information, be out of date, or contain factual errors.
© 2001-2016 Internet Systems ConsortiumPlease help us to improve the content of our knowledge base by letting us know below how we can improve this article. If you have a technical question or problem on which you'd like help, please don't submit it here as article feedback. 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.