Knowledge Base ISC Main Website Ask a Question/Contact ISC
CVE-2004-0461: DHCPD contains C Includes that sometimes defines vsnprintf() as vsprintf()
Author: Cathy Almond Reference Number: AA-00960 Views: 4358 Created: 2013-05-29 14:31 Last Updated: 2013-05-30 11:41 0 Rating/ Voters

DHCPD, when compiled in environments that do not provide the vsnprintf function, uses C include files that define vsnprintf to use the less safe vsprintf function

Posting date: 
22 Jun 2004
Program Impacted: 
Versions affected: 
3.0.1rc12, 3.0.1rc13


ISC DHCP makes use of the vsnprintf() function for writing various log file strings. For systems that do not support vsnprintf(), a C include file was created that defines the vsnprintf() function to vsprintf() as such:

#define vsnprintf(buf, size, fmt, list) vsprintf (buf, fmt, list)

vsprintf() is a function that does not check bounds, therefore the size is discarded creating the potential for a buffer overflow when client provided data is supplied. Note that the vsnprintf() statements are defined after the vulnerable code that is discussed in VU#317350. This means that VU#317350 would be triggered prior to these potential buffer overflows, unless a client could specify content to a vsnprintf() statement not associated with logging. It is believed that there aren't any other vsnprintf() statements vulnerable to this type of exploitation.



Active exploits:

None known at this time.


Upgrade to a released version of ISC DHCPD.

Related Documents:

If you'd like more information on our Forum or product support please visit

Do you still have questions?  Questions regarding this advisory should go to

Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected.

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