Security Advisory Important: dhcp security update

Advisory: RHSA-2011:0840-1
Type: Security Advisory
Severity: Important
Issued on: 2011-05-31
Last updated on: 2011-05-31
Affected Products: Red Hat Enterprise Linux ELS (v. 3)
CVEs ( 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.

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

Updated packages

Red Hat Enterprise Linux ELS (v. 3)

dhcp-3.0.1-10.3_EL3.src.rpm     MD5: cbd6722d8594eb59f555230b789952e8
SHA-256: b8d809e54e61209e2da2452863fe7a0169499bfbb479602af29efd8a903cc419
dhclient-3.0.1-10.3_EL3.i386.rpm     MD5: f3818ccd243dc9f414ea9c6f308d1602
SHA-256: fe26eb30231826d68facd058a5172abad5537724d44ab90528b7f37dc1940d7c
dhcp-3.0.1-10.3_EL3.i386.rpm     MD5: a7eaf97daacd579a4f418cdc14989465
SHA-256: 209e8a39094d8badcb56fef23db638d17671ed94bd6fb8d8413a183c458069d6
dhcp-devel-3.0.1-10.3_EL3.i386.rpm     MD5: f369d35fef65f680500cca3ee036b844
SHA-256: e0766e85d4d83aeafe77eda63d4f738542ae43da99507a93996d9a683c66d499
(The unlinked packages above are only available from the Red Hat Network)

Bugs fixed (see bugzilla for more information)

689832 - CVE-2011-0997 dhclient: insufficient sanitization of certain DHCP response values


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 More contact details at