OpenSSL v1.0.1.a Release NotesRelease Date: 2012-04-26 // about 10 years ago
- OpenSSL 1.0.0 sets SSL_OP_ALL to 0x80000FFFL and OpenSSL 1.0.1 and 1.0.1a set SSL_OP_NO_TLSv1_1 to 0x00000400L which would unfortunately mean any application compiled against OpenSSL 1.0.0 headers setting SSL_OP_ALL would also set SSL_OP_NO_TLSv1_1, unintentionally disabling TLS 1.1 also. Fix this by changing the value of SSL_OP_NO_TLSv1_1 to 0x10000000L Any application which was previously compiled against OpenSSL 1.0.1 or 1.0.1a headers and which cares about SSL_OP_NO_TLSv1_1 will need to be recompiled as a result. Letting be results in inability to disable specifically TLS 1.1 and in client context, in unlike event, limit maximum offered version to TLS 1.0 [see below].
- In order to ensure interoperability SSL_OP_NO_protocolX does not
disable just protocol X, but all protocols above X if there are
protocols below X still enabled. In more practical terms it means
that if application wants to disable TLS1.0 in favor of TLS1.1 and
above, it's not sufficient to pass
SSL_OP_NO_TLSv1, one has to pass
SSL_OP_NO_TLSv1|SSL_OP_NO_SSLv3|SSL_OP_NO_SSLv2. This applies to client side.