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Where can I get the definitive list of weak ciphers? Various tools are listing ciphers as weak but these vary somewhat. Which CBC ciphers specifically currently suffer with known weaknesses and where can I get more information on this?

The two cipher suites I am investigating are: TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 and TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384

https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-4 lists them both as DTLS-OK -Y but not recommended; Recommended - N. Not very proficient in reading RFCs so the linked RFC8422(https://www.rfc-editor.org/rfc/rfc8422.html) doesn't help as far as I can see?

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    ALL ciphersuites using CBC in 1.2 (and below, which is now deprecated, where they were the only ones other than RC4 which is also deprecated) are subject to Lucky13 unless EtM is used or the implementation is very careful about constant-time. 3DES-CBC for huge data allows detecting repeated post-XOR blocks which isn't much of an attack. 1DES is broken and must be used any way. If you actually want security and not just checklisting, there are many other things more important than the ciphersuite(s); see RFC9325 and Ivan Ristic's 'Bulletproof TLS' to start.
    – dave_thompson_085
    Commented Aug 26 at 2:42

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There isn't a definitive list, because as always the question is: what exactly do you mean by "weak"?

And even if you can agree on that, it's not quite that simple - because it's not just the ciphersuite that matters but also the TLS version that you're using. And there are also weaknesses in specific TLS implementations that may be relevant or may not be.

The recommendations given by Mozilla are generally well respected - but as always will depend somewhat on your threat model and the level of compatibility that you need.

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