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DHCPCD Character Expansion Remote Command Execution Vulnerability

When assigning an IP address to a network interface, dhcpcd may execute an external script, '/sbin/dhcpd-<interface>.exe'. This is an optional configuration that must be setup manually on Conectiva systems (others are not confirmed) by copying the script into /sbin/.

The script 'dhcpcd-<interface>.exe' uses values from '/var/lib/dhcpcd/dhcpcd-<interface>.info', which originate from the DHCP server. A lack of input validation on this data may make it possible for commands injected by a malicious DHCP server to be executed through the use of shell metacharacters such as ';' and '|'. These commands may run with root privileges.