FreeBSD Security Advisory FreeBSD-SA-00:34 - ISC-DHCP is an implementation of the DHCP protocol containing client and server. FreeBSD 3.2 and above includes the version 2 client by default in the base system, and the version 2 and version 3 clients and servers in the Ports Collection. The dhclient utility (DHCP client), versions 2.0pl2 and before (for the version 2.x series), and versions 3.0b1pl16 and before (for the version 3.x series) does not correctly validate input from the server, allowing a malicious DHCP server to execute arbitrary commands as root on the client. DHCP may be enabled if your system was initially configured from a DHCP server at install-time, or if you have specifically enabled it after installation. FreeBSD 4.1 is not affected by this problem since it contains the 2.0pl3 client.