CVE-2005-2531: Openvpn

Medium severity, CVSS 5.0. EPSS: 2% chance of exploitation in the next 30 days.

OpenVPN before 2.0.1, when running with "verb 0" and without TLS authentication, does not properly flush the OpenSSL error queue when a client fails certificate authentication to the server and causes the error to be processed by the wrong client, which allows remote attackers to cause a denial of service (client disconnection) via a large number of failed authentication attempts.

Affected products

• Openvpn Openvpn: version 2.0 only; version 2.0.1_rc1 only; version 2.0.1_rc2 only; version 2.0.1_rc3 only; version 2.0.1_rc4 only; version 2.0.1_rc5 only; …

Published 2005-08-24. Last modified 2026-06-16.