The SSL/TLS server implementation in OpenSSL 0.9.7 before 0.9.7h and 0.9.8 before 0.9.8a when using the SSL_OP_MSIE_SSLV2_RSA_PADDING option disables a verification step that is required for preventing protocol version rollback attacks which allows remote attackers to force a client and server to use a weaker protocol than needed via a man-in-the-middle attack.