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Ubuntu Security Notice USN-1108-2
April 19, 2011

dhcp3 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 10.10
- Ubuntu 10.04 LTS
- Ubuntu 9.10

Summary:

An attacker's DHCP server could send crafted responses to your computer and
cause it to run programs as root.

Software Description:
- dhcp3: DHCP Client

Details:

USN-1108-1 fixed vulnerabilities in DHCP. Due to an error, the patch to fix
the vulnerability was not properly applied on Ubuntu 9.10 and higher. This
update fixes the problem.

Original advisory details:

 Sebastian Krahmer discovered that the dhclient utility incorrectly filtered
 crafted responses. An attacker could use this flaw with a malicious DHCP
 server to execute arbitrary code, resulting in root privilege escalation.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 10.10:
  dhcp3-client                    3.1.3-2ubuntu6.2

Ubuntu 10.04 LTS:
  dhcp3-client                    3.1.3-2ubuntu3.2

Ubuntu 9.10:
  dhcp3-client                    3.1.2-1ubuntu7.3

In general, a standard system update will make all the necessary changes.

References:
  CVE-2011-0997

Package Information:
  https://launchpad.net/ubuntu/+source/dhcp3/3.1.3-2ubuntu6.2
  https://launchpad.net/ubuntu/+source/dhcp3/3.1.3-2ubuntu3.2
  https://launchpad.net/ubuntu/+source/dhcp3/3.1.2-1ubuntu7.3