Chapter 23. Security

A runtime version of OpenSSL is masked and SSL_OP_NO_TLSv1_1 must not be used when an application runs with OpenSSL 1.0.0

Because certain applications perform incorrect version check of the OpenSSL version, the actual runtime version of OpenSSL is masked and the build-time version is reported instead. Consequently, it is impossible to detect the currently running OpenSSL version using the SSLeay() function.
Additionally, passing the value equivalent to the SSL_OP_NO_TLSv1_1 option as present on OpenSSL 1.0.1 to the SSL_CTX_set_options() function when running with OpenSSL 1.0.0 breaks the SSL/TLS support completely.
To work around this problem, use another way to detect the currently running OpenSSL version. For example, it is possible to obtain a list of enabled ciphers with the SSL_get_ciphers() function and search a TLS 1.2 cipher by parsing the list using the SSL_CIPHER_description() function. This indicates an application that runs with the OpenSSL version later than 1.0.0 because TLS 1.2 support is present since version 1.0.1. (BZ#1497859)