Offer modern AEAD ciphers

Why it matters

The server offers only older CBC ciphers for TLS 1.2 and no TLS 1.3, so no client gets the modern authenticated ciphers (AES-GCM or ChaCha20). CBC suites have a history of attacks and are slower.

Staged change. Do this in stages and check each one before the next, so a mistake does not break your site or your mail.

The fix

1. Set the cipher list to ECDHE with AES-GCM and ChaCha20, as in the snippets for your server, and enable TLS 1.3 if the TLS library supports it.
2. If the server cannot offer these ciphers, its TLS library is too old. Update it, or put a modern CDN or reverse proxy in front.
3. Stage the change, test with the command below and keep the old setting to roll back.

nmap --script ssl-enum-ciphers -p 443 example.com

The examples use example.com. Replace it with your own domain.

Read the documentation ↗(opens in a new tab)

Related

• Reported by the cipher suites check
• Disable the RC4 cipher
• Disable the 3DES cipher
• Require forward-secret ciphers
• Retire the old TLS versions that use CBC ciphers