--- title: "CVE-2009-0692: DHCP Stack Overflow in 'dhclient' script_write_params" slug: "aa-00962" description: "CVE-2009-0692: DHCP Stack Overflow in 'dhclient' script_write_params()" tags: ["isc dhcp"] updated: 2025-03-24T21:55:51Z published: 2025-03-24T21:55:51Z canonical: "kb.isc.org/aa-00962" --- > ## Documentation Index > Fetch the complete documentation index at: https://kb.isc.org/llms.txt > Use this file to discover all available pages before exploring further. # CVE-2009-0692: DHCP Stack Overflow in 'dhclient' script_write_params() ISC dhclient has a stack overflow vulnerability which makes it theoretically possible for a rogue DHCP server to execute arbitrary commands as root on the affected system through stack return subversion. CVE: [CVE-2009-0692](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-0692) Posting date: 14 Jul 2009 Program Impacted: [DHCP](https://www.isc.org/software/dhcp) Versions affected: DHCP 4.1 (all versions), 4.0 (all versions), 3.1 (all versions), 3.0 (all versions), 2.0 (all versions) Severity: High Exploitable: Remotely **Description:** While generating a subnet number from the server-supplied leased address and subnet-mask 'dhclient' copies the information into a field without verifying if the length of the information exceeds the length of the field. Theoretically this allows a rogue DHCP server to execute arbitrary commands as root on the affected system through stack return subversion. This attack has little to no risk for a client situated on a network that is well defended, whereas clients that are roaming to potentially hostile or ad-hoc networks can see this attack to pose a severe threat. Factors complicating any attack would be: 1.The attacker would need to generate messages the client views as authentic. 2.The attacker would then need to develop their attack within a limited packet size. **Workarounds:** There is no known workaround, you must install the patches listed below to protect the DHCP client. **Active exploits:** None known at this time **Solution:** ``` Upgrade to 4.1.0p1, 4.0.1p1, or 3.1.2p1 ``` There are no fixes planned for DHCP 3.0 or DHCP 2.0, as those release trains have reached End-Of-Life. **Acknowledgements:** Credit: Mandriva Linux Engineering Team and for discovering and reporting the software flaw. **Related Documents:** If you'd like more information on our Forum or product support please visit [www.isc.org/support](http://www.isc.org/support). **Do you still have questions?** Questions regarding this advisory should go to [security-officer@isc.org](mailto:security-officer@isc.org) **Note:** ISC patches only [currently supported versions](http://www.isc.org/software/dhcp/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: [https://www.isc.org/security-vulnerability-disclosure-policy](https://www.isc.org/security-vulnerability-disclosure-policy) This Knowledge Base article [https://kb.isc.org/docs/aa-00962](https://kb.isc.org/docs/aa-00962) 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](https://lists.isc.org/mailman/listinfo) and/or posting your question there (you will need to register there first for your posts to be accepted). The [bind-users](https://lists.isc.org/mailman/listinfo/bind-users) and the [dhcp-users](https://lists.isc.org/mailman/listinfo/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](https://www.isc.org/support).