OpenVPN 2.7alpha1 through 2.7.5 using mbedTLS allows remote authenticated users to be misidentified by ignoring the configured X.509 username identity lookup field

The Windows interactive service in OpenVPN 2.4.0 through 2.6.21 and 2.7alpha1 through 2.7.5 allows local authenticated users to bypass the trusted configuration directory constraint and load arbitrary configuration files via crafted options that bypass whitelist checks

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

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 8 July 2026

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

The Windows interactive service in OpenVPN 2.7alpha1 through 2.7.4 allows remote attackers to cause persistent DNS state pollution or a service crash via a crafted search domain during the disconnection process

Last updated 10 July 2026

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 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).

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.

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.

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.

Insufficient epoch key slot processing in OpenVPN 2.7alpha1 through 2.7rc5 allows remote authenticated users to trigger an assert resulting in a denial of service

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

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.

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

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

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.

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.

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).

An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (PDATAV2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSHREPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.

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.

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.

Last updated 11 March 2025

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

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 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.