ISC Security Advisory: Reducing the Expiration Time For an IPv6 Lease May Cause the Server to Crash
mcnally at isc.org
Wed Sep 12 18:40:21 UTC 2012
This email advisory is provided for your information. The most
up to date advisory information will always be at:
https://kb.isc.org/article/AA-00779 please use this URL for the
most up to date advisory information.
CVE-2012-3955: Reducing the expiration time for an IPv6 lease may cause the server to crash
Document Version: 2.0
Posting date: 12 September 2012
Program Impacted: ISC DHCP 4
Versions affected: 4.1.x, 4.2.x
Exploitable: From networks permitted to send requests to the DHCP server.
ISC has discovered that reducing the expiration time for an
active IPv6 lease may cause the server to crash.
Please Note: Versions of ISC DHCP 4.0 may also be affected, but
these branches are beyond their "end of life" (EOL) and no longer
receive testing or security fixes from ISC. For current information
on which versions are actively supported, please see
Affected servers can terminate unexpectedly, resulting in a
denial of service condition for clients.
CVSS Score: 5.7
CVSS Equation: (AV:A/AC:M/Au:N/C:N/I:N/A:C)
For more information on the Common Vulnerability Scoring System
and to obtain your specific environmental score please visit:
ISC recommends setting a value for the default-lease-time option
in the configuration file, and not reducing it once set.
No known active exploits.
Upgrade to the updated release most closely related to your
current version of DHCP. These can be downloaded from
ISC DHCP version 4.1-ESV-R7
ISC DHCP version 4.2.4-P2
ISC would like to thank Glen Eustace of Massey University, New
Zealand for finding this issue.
Document Revision History:
1.0 - 4 Sept. 2012 Advance Notification to Phase 1
1.1 - 11 Sept. 2012 Phase 2 & 3 notified
2.0 - 12 Sept. 2012 Phase 4 - Public Released
If you'd like more information on our Forum or product support
please visit www.isc.org/software/guild or www.isc.org/support.
Do you still have questions? Questions regarding this advisory
should go to security-officer at isc.org
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 https://kb.isc.org/article/AA-00779 is
the complete and official security advisory document. There is
also a summary article located on our website and linking to here:
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