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.

OpenVPN 2.x before 2.0.4, when running in TCP mode, allows remote attackers to cause a denial of service (segmentation fault) by forcing the accept function call to return an error status, which leads to a null dereference in an exception handler.