dhclient, dhcp, libdhcp4client security update

CentOS Errata and Security Advisory CESA-2012:1140

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
address.

A denial of service flaw was found in the way the dhcpd daemon handled
zero-length client identifiers. A remote attacker could use this flaw to
send a specially-crafted request to dhcpd, possibly causing it to enter an
infinite loop and consume an excessive amount of CPU time. (CVE-2012-3571)

Upstream acknowledges Markus Hietava of the Codenomicon CROSS project as
the original reporter of this issue.

Users of DHCP should upgrade to these updated packages, which contain a
backported patch to correct this issue. After installing this update, all
DHCP servers will be restarted automatically.

Merged security bulletin from advisories:
https://lists.centos.org/pipermail/centos-announce/2012-August/080945.html

Affected packages:
dhclient
dhcp
dhcp-devel
libdhcp4client
libdhcp4client-devel

Upstream details at:
https://access.redhat.com/errata/RHSA-2012:1140