This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu.
Details follow:
Nahuel Riva and Gerardo Richarte discovered that the DHCP server did not correctly handle certain client options. A remote attacker could send malicious DHCP replies to the server and execute arbitrary code.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 6.06 LTS: dhcp 2.0pl5-19.4ubuntu0.1
Ubuntu 6.10: dhcp 2.0pl5-19.4ubuntu1.1
Ubuntu 7.04: dhcp 2.0pl5-19.5ubuntu2.1
Ubuntu 7.10: dhcp 2.0pl5dfsg1-20ubuntu1.1
In general, a standard system upgrade is sufficient to affect the necessary changes.