Last updated 11 March 2025

Use after free in OpenVPN version 2.6.0 to 2.6.6 may lead to undefined behavoir, leaking memory buffers or remote execution when sending network buffers to a remote peer.

Insufficient argument validation in OpenVPN 2.7alpha1 through 2.7rc1 allows an attacker to trigger a heap buffer over-read when parsing IP addresses

DISPUTED A cross-protocol scripting issue was discovered in the management interface in OpenVPN through 2.4.5. When this interface is enabled over TCP without a password, and when no other clients are connected to this interface, attackers can execute arbitrary management commands, obtain sensitive information, or cause a denial of service (SIGTERM) by triggering XMLHttpRequest actions in a web browser. This is demonstrated by a multipart/form-data POST to http://localhost:23000 with a "signal SIGTERM" command in a TEXTAREA element. NOTE: The vendor disputes that this is a vulnerability. They state that this is the result of improper configuration of the OpenVPN instance rather than an intrinsic vulnerability, and now more explicitly warn against such configurations in both the management-interface documentation, and with a runtime warning.

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.

OpenVPN 2.7alpha1 through 2.7beta1 on POSIX based platforms allows a remote authenticated server to inject shell commands via DNS variables when --dns-updown is in use

OpenVPN before version 2.5.3 on Windows allows local users to load arbitrary dynamic loadable libraries via an OpenSSL configuration file if present, which allows the user to run arbitrary code with the same privilege level as the main OpenVPN process (openvpn.exe).

openvpnserv.exe (aka the interactive service helper) in OpenVPN 2.4.x before 2.4.6 allows a local attacker to cause a double-free of memory by sending a malformed request to the interactive service. This could cause a denial-of-service through memory corruption or possibly have unspecified other impact including privilege escalation.

Improper validation of source IP addresses in OpenVPN version 2.6.0 through 2.6.15 and 2.7alpha1 through 2.7rc1 allows an attacker to open a session from a different IP address which did not initiate the connection resulting in a denial of service for the originating client

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 versions before 2.4.3 and before 2.3.17 are vulnerable to remote denial-of-service when receiving malformed IPv6 packet.

OpenVPN version 2.3.12 and newer is vulnerable to unauthenticated Denial of Service of server via received large control packet. Note that this issue is fixed in 2.3.15 and 2.4.2.

OpenVPN versions before 2.4.3 and before 2.3.17 are vulnerable to denial-of-service and/or possibly sensitive memory leak triggered by man-in-the-middle attacker.

OpenVPN 3 Core Library version 3.6 and 3.6.1 allows a man-in-the-middle attacker to bypass the certificate authentication by issuing an unrelated server certificate using the same hostname found in the verify-x509-name option in a client configuration.

An authenticated remote attacker with high privileges can exploit the OpenVPN configuration via the web-based management interface of a WAGO PLC. If user-defined scripts are permitted, OpenVPN may allow the execution of arbitrary shell commands enabling the attacker to run arbitrary commands on the device.

A memory leak in the tls-crypt-v2 client key extraction in OpenVPN 2.5.0 through 2.6.20 and 2.7alpha1 through 2.7.4 allows remote attackers to cause a denial of service (memory exhaustion) via a flood of crafted packets

Last updated 8 July 2026

Improper validation of packet length during tls-crypt-v2 key extraction in OpenVPN 2.6.0 through 2.6.19 and 2.7alpha1 through 2.7.1 allows authenticated attackers to trigger a fatal assertion and cause a denial of service via a specially crafted packet.

OpenVPN versions before 2.4.3 and before 2.3.17 are vulnerable to denial-of-service by authenticated remote attacker via sending a certificate with an embedded NULL character.

OpenVPN versions before 2.3.15 and before 2.4.2 are vulnerable to reachable assertion when packet-ID counter rolls over resulting into Denial of Service of server by authenticated attacker.

A race condition in OpenVPN 2.6.0 through 2.6.19 and 2.7alpha1 through 2.7.1 allows remote attackers to potentially cause a server crash or leak heap memory via a use-after-free triggered during TLS session promotion.

A memory leak in OpenVPN version 2.5.0 through 2.5.11, 2.6.0 through 2.6.20 and 2.7alpha1 through 2.7.4 allows remote attackers with a valid tls-crypt-v2 client key to potentially cause a denial of service

An incomplete guard in OpenVPN 2.6.0 through 2.6.20 and 2.7alpha1 through 2.7.4 allows remote authenticated peers to trigger a use-after-free during TLS session promotion, potentially leading to a denial of service or memory leakage

A use-after-free in OpenVPN 2.6.0 through 2.6.20 and 2.7alpha1 through 2.7.4 allows remote authenticated peers to potentially cause a denial of service or leak memory via crafted packets during TLS session promotion or expiry

Last updated 10 July 2026

OpenVPN versions before 2.4.3 and before 2.3.17 are vulnerable to remote denial-of-service due to memory exhaustion caused by memory leaks and double-free issue in extractx509extension().

OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a "Sweet32" attack.

An incorrect buffer size calculation in the epoch key generator in OpenVPN ovpn-dco-win version 2.0.0 through 2.8.3 allows a remote authenticated peer to trigger a heap-based buffer overflow and kernel memory corruption via a crafted data packet, resulting in a system crash (denial of service).

Interactive service agent in OpenVPN version 2.5.0 through 2.6.16 and 2.7alpha1 through 2.7rc2 on Windows allows a local authenticated user to connect to the service and trigger an error causing a local denial of service.

Unquoted Windows search path vulnerability in the ptservice service prior to PrivateTunnel version 3.0 (Windows) and OpenVPN Connect version 3.1 (Windows) allows local users to gain privileges via a crafted program.exe file in the %SYSTEMDRIVE% folder.