I am trying to verify whether I am vulnerable to the OpenSSL TLS renegotiation vulnerability CVE-2021-3449 (fixed in OpenSSL 1.1.1k). When I connect to the website using openssl s_client -tls1_2 -connect example.com:443 , it says "Secure Renegotiation IS supported". When I then send the request for renegotiation, it disconnects:
$ openssl s_client -tls1_2 -connect example.com:443 [. ] --- GET / HTTP/1.1 R RENEGOTIATING depth=2 O = Digital Signature Trust Co., CN = DST Root CA X3 verify return:1 depth=1 C = US, O = Let's Encrypt, CN = R3 verify return:1 depth=0 CN = verify return:1 write:errno=0 Does that mean I am safe since since Client-Initiated Renegotiation is disabled? I don't know when or why my web server would ever choose to renegotiate of its own accord. A PoC that I can test against my server would also be appreciated.