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             AUSCERT External Security Bulletin Redistribution

An Error in DDNS Processing of DHCPv6 Leases Can Cause a Crash in ISC dhcpd
                              17 January 2012


        AusCERT Security Bulletin Summary

Product:           DHCP
Publisher:         Internet Systems Consortium
Operating System:  UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        None
CVE Names:         CVE-2011-4868  

Original Bulletin: 

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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. 

CVE: CVE-2011-4868 
Document Version: 1.2 
Posting date: 12 Jan 2012 
Program Impacted: DHCP 
Versions affected: 4.2.2, 4.2.3, 4.2.3-P1 
Severity: High 
Exploitable: remotely 


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. Solution:

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:


    Do you have Questions? Questions regarding this advisory should go to 
security-officer@isc.org. 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

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