OpenVPN PUSH_REPLY Message Injection Vulnerability in Control Channel Logging

A vulnerability exists in OpenVPN versions prior to 2.6.11, where the software fails to properly sanitize PUSH_REPLY messages. This flaw allows an attacker controlling the server to inject unexpected arbitrary data into client logs. Additionally, this vulnerability could lead to a high CPU load on the client side.

Impact

Exploitation of this vulnerability can cause arbitrary data injection into client logs, potentially leading to log pollution or misuse of log information. Furthermore, according to the OpenVPN release announcement, this vulnerability could cause a high CPU load on the affected client.

Remediation

Users can upgrade to OpenVPN version 2.6.11, available for download from the OpenVPN community downloads page. Debian and Ubuntu packages can be obtained from the official APT repositories, while Red Hat derivatives can use the Fedora Copr repository.