TLS Versions Explained: Why TLS 1.0/1.1 Are Weak and What 'Modern TLS' Means
Last updated August 9, 2026.
TLS is the protocol, the certificate is just one part of it
TLS (Transport Layer Security) is the protocol that negotiates encryption for a connection. The certificate is presented as part of that negotiation, but the protocol version itself — TLS 1.0 through 1.3 — determines which cryptographic algorithms and handshake behaviors are allowed, independent of whether the certificate is otherwise valid.
Why TLS 1.0 and 1.1 are considered weak
TLS 1.0 (1999) and TLS 1.1 (2006) predate a number of cryptographic attacks and no longer support the cipher suites and handshake protections built into later versions. Major browsers formally deprecated both in 2020, and PCI DSS has required disabling them for payment-handling systems since 2018. A server that still negotiates TLS 1.0/1.1 is not automatically breached by that fact alone, but it is running a protocol version its own ecosystem no longer considers acceptable.
What 'modern TLS' means
In practice, modern TLS means supporting TLS 1.2 at minimum and preferring TLS 1.3, while disabling TLS 1.0 and 1.1 at the server or load-balancer level. TLS 1.3, finalized in 2018, also simplifies the handshake and removes several legacy cipher options that were sources of past vulnerabilities.
How this shows up in a scan
A certificate and configuration checker looks at which protocol version a server actually negotiates during a normal TLS handshake — the same negotiation a browser performs — and flags it if the server still allows TLS 1.0 or 1.1, separately from whether the certificate itself is valid.
FAQ
What is the latest version of TLS?
TLS 1.3, published as RFC 8446. It removes obsolete cryptographic algorithms that earlier versions still allowed and cuts the handshake to one round trip, making connections both faster and harder to misconfigure insecurely.
What's the difference between TLS 1.2 and TLS 1.3?
TLS 1.3 drops support for weak/legacy ciphers that TLS 1.2 still permits (like RC4 and static RSA key exchange), encrypts more of the handshake itself, and reduces the handshake to one round trip instead of two — so it's both more secure and lower-latency.
Are TLS 1.0 and 1.1 still safe to use?
No. Both were formally deprecated by RFC 8996 in 2021 and are considered insecure — they lack protections against known attacks like BEAST and don't support the cipher suites modern security guidance requires. Major browsers stopped supporting them by default years ago.
What's the difference between SSL and TLS?
TLS is the successor to SSL — SSL 1.0 through 3.0 are all obsolete and insecure, and TLS 1.0 was effectively "SSL 3.1" before being renamed. "SSL certificate" and "SSL/TLS certificate" are still used interchangeably in casual usage, but the protocol actually negotiated by any modern server is TLS, not SSL.
How do I check which TLS version a website uses?
Point a checker like Nivaronix's SSL/TLS checker at the domain — it reports the negotiated protocol version alongside certificate expiry, hostname match, and chain issues in one pass.
Check which TLS version your domain negotiates
The SSL/TLS checker flags TLS 1.0/1.1 alongside certificate expiry, hostname mismatch, and chain issues, and that result feeds directly into the overall security score for the domain.
Open the SSL/TLS checker