CVE-2011-4868: An Error in DDNS Processing of DHCPv6 Leases Can Cause a Crash in ISC dhcpd


Improper handling of Dynamic DNS information associated with DHCPv6 leases can cause a segmentation fault in ISC DHCP servers using IPv6 and Dynamic DNS, resulting in denial of service to clients.

Document Version:          
Posting date: 
12 Jan 2012
Program Impacted: 
Versions affected: 
4.2.2, 4.2.3, 4.2.3-P1


Due to improper handling of a DHCPv6 lease structure, ISC DHCP servers that are serving IPv6 address pools AND using Dynamic DNS can encounter a segmentation fault error while updating lease status under certain conditions. The potential exists for this condition to be intentionally triggered, resulting in effective denial of service to clients expecting service from the affected server. Users of affected versions who use DHCPv6 and Dynamic DNS should upgrade to version 4.2.3-P2.

CVSS Score: 6.1

CVSS Equation:

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit:


No known workarounds, please upgrade if you are running an affected version of ISC DHCP and you use Dynamic DNS and IPv6.

Active exploits: 

None known at this time.

Upgrade to ISC DHCP 4.2.3-P2

DHCP 4.2.3-P2 can be downloaded from the following location:

Document Revision History:

1.0 05 January 2012 - Phase I notified

1.1 11 January 2012 - Phase II & III notified

1.2 12 January 2012 - Public Release

Related Document: 

This security advisory is a copy of the official document located on our website: