Race condition in OpenVPN before 2.0.1, when --duplicate-cn is not enabled, allows remote attackers to cause a denial of service (server crash) via simultaneous TCP connections from multiple clients that use the same client certificate.
http://www.securityfocus.com/bid/14610
http://www.mandriva.com/security/advisories?name=MDKSA-2005:145
http://www.debian.org/security/2005/dsa-851
http://secunia.com/advisories/17103