dhclient, dhcp security update

CentOS Errata and Security Advisory CESA-2011:1819

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 DHCP
request packets when regular expression matching was used in
“/etc/dhcp/dhcpd.conf”. A remote attacker could use this flaw to crash
dhcpd. (CVE-2011-4539)

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/2011-December/080501.html

Affected packages:
dhclient
dhcp
dhcp-common
dhcp-devel

Upstream details at:
https://access.redhat.com/errata/RHSA-2011:1819