OpenVPN 2.0 through 2.0.5 allows remote malicious servers to execute arbitrary code on the client by using setenv with the LDPRELOAD environment variable.

Format string vulnerability in the foreignoption 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.

OpenVPN 2.0.7 and earlier, when configured to use the --management option with an IP that is not 127.0.0.1, uses a cleartext password for TCP sessions to the management interface, which might allow remote attackers to view sensitive information or cause a denial of service.