Too Early
Production Risk
Low. This is a security mechanism. A compliant client will handle it automatically, leading only to a slight performance penalty on the initial request.
Indicates that the server is unwilling to risk processing a request that might be replayed. This is used in the context of 0-RTT (Zero Round Trip Time Resumption) in TLS 1.3, where a client sends data in the first flight of messages, which could be vulnerable to a replay attack.
- 1A client attempts to POST data using TLS 1.3's early data feature (0-RTT).
- 2The server is configured to not accept early data for that endpoint to prevent replay attacks.
- 3The server sends this status to instruct the client to retry the request securely after the TLS handshake is fully complete.
A mobile app sends POST data in the initial TLS 1.3 handshake packet to improve latency, but the server rejects it as a security precaution.
(A POST request sent using TLS 1.3 0-RTT)
expected output
HTTP/1.1 425 Too Early
Fix
Retry After Handshake Completion
WHEN A client receives a 425 response.
The client should automatically and transparently retry the request over the now fully established TLS connection.
Why this works
Client-Side TLS Implementation
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