OpenVPN Access Server 2.8.x before 2.8.1 allows LDAP authentication bypass (except when a user is enrolled in two-factor authentication).

CRLF injection vulnerability in the web interface in OpenVPN Access Server 2.1.4 allows remote attackers to inject arbitrary HTTP headers and consequently conduct session fixation attacks and possibly HTTP response splitting attacks via "%0A" characters in the PATH_INFO to __session_start__/.

OpenVPN 2.x before 2.0.11, 2.1.x, 2.2.x before 2.2.3, and 2.3.x before 2.3.6 allows remote authenticated users to cause a denial of service (server crash) via a small control channel packet.

Multiple cross-site request forgery (CSRF) vulnerabilities in the XML-RPC API in the Desktop Client in OpenVPN Access Server 1.5.6 and earlier allow remote attackers to hijack the authentication of administrators for requests that (1) disconnecting established VPN sessions, (2) connect to arbitrary VPN servers, or (3) create VPN profiles and execute arbitrary commands via crafted API requests.

Cross-site request forgery (CSRF) vulnerability in the Admin web interface in OpenVPN Access Server before 1.8.5 allows remote attackers to hijack the authentication of administrators for requests that create administrative users.

The openvpn_decrypt function in crypto.c in OpenVPN 2.3.0 and earlier, when running in UDP mode, allows remote attackers to obtain sensitive information via a timing attack involving an HMAC comparison function that does not run in constant time and a padding oracle attack on the CBC mode cipher.

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.

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

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.

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.