Format string vulnerability in the foreign_option function in options.c for OpenVPN 2.0.x allows remote clients to execute arbitrary code via format string specifiers in a push of the dhcp-option command option.
http://www.vupen.com/english/advisories/2005/2255
http://www.securityfocus.com/bid/15239
http://www.securityfocus.com/archive/1/415487
http://www.novell.com/linux/security/advisories/2005_25_sr.html
http://www.gentoo.org/security/en/glsa/glsa-200511-07.xml
http://www.debian.org/security/2005/dsa-885
http://secunia.com/advisories/17480
http://secunia.com/advisories/17452
http://secunia.com/advisories/17447
http://secunia.com/advisories/17376