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AUSCERT External Security Bulletin Redistribution
Important: dhcp security update
1 June 2011
AusCERT Security Bulletin Summary
Publisher: Red Hat
Operating System: Red Hat Enterprise Linux AS/ES/WS 3
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
CVE Names: CVE-2011-0997
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Red Hat Security Advisory
Synopsis: Important: dhcp security update
Advisory ID: RHSA-2011:0840-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2011-0840.html
Issue date: 2011-05-31
CVE Names: CVE-2011-0997
Updated dhcp packages that fix one security issue are now available for
Red Hat Enterprise Linux 3 Extended Life Cycle Support.
The Red Hat Security Response Team has rated this update as having
important security impact. A Common Vulnerability Scoring System (CVSS)
base score, which gives a detailed severity rating, is available from the
CVE link in the References section.
2. Relevant releases/architectures:
Red Hat Enterprise Linux AS (v. 3 ELS) - i386
Red Hat Enterprise Linux ES (v. 3 ELS) - i386
The Dynamic Host Configuration Protocol (DHCP) is a protocol that allows
individual devices on an IP network to get their own network configuration
information, including an IP address, a subnet mask, and a broadcast
It was discovered that the DHCP client daemon, dhclient, did not
sufficiently sanitize certain options provided in DHCP server replies, such
as the client hostname. A malicious DHCP server could send such an option
with a specially-crafted value to a DHCP client. If this option's value was
saved on the client system, and then later insecurely evaluated by a
process that assumes the option is trusted, it could lead to arbitrary code
execution with the privileges of that process. (CVE-2011-0997)
Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for
reporting this issue.
All dhclient users should upgrade to these updated packages, which contain
a backported patch to correct this issue.
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.
This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
5. Bugs fixed (http://bugzilla.redhat.com/):
689832 - CVE-2011-0997 dhclient: insufficient sanitization of certain DHCP response values
6. Package List:
Red Hat Enterprise Linux AS (v. 3 ELS):
Red Hat Enterprise Linux ES (v. 3 ELS):
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is <email@example.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2011 Red Hat, Inc.
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