Reject TLS 1.0 negotiation
02Supporting a modern protocol must not leave TLS 1.0 as an available fallback.
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“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 4 ↗
RFC 8996 · § 4EXAMPLE
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03
Keep protected resources behind the policy.
A client must upgrade before it can connect.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
RFC 7525 § 3.1.1: SHOULD NOTRFC 8996 §§ 4, 6: MUST NOT
The earlier recommendation against TLS 1.0 becomes an explicit prohibition on its negotiation.
Read the updated RFC section ↗TLS 1.0 MUST NOT be used.
- Implementations MUST NOT negotiate TLS 1.0.
- A peer receiving a Hello offering TLS 1.0 as the negotiated version must send protocol_version and close.
- The legacy record-layer version of a ClientHello is a separate compatibility field; it is not permission to negotiate TLS 1.0.
Do not reject a modern handshake merely because its ClientHello record uses a legacy {03,XX} value. The RFC explicitly preserves record-layer compatibility.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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