> An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack.

> A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue.

TLS Renegotiation strikes again!

One of the best parts of TLS 1.3 is that they completely scrapped it. So, IIUC, if you're running only TLS 1.3 then the NULL deference for the (enabled by default) feature in TLS 1.2 will not impact you.

Also a lot of end user facing software such as nginx has renegotiation explicitly disabled so hopefully this won't be particularly far reaching.