field Registered
Verified 2026-09-18 · registry updated
2026-08-28Early-Data
Signals that a request was sent in TLS 1.3 early data.
Use Early-Data with replay-safe handling and return 425 Too Early when a request must not be processed before replay risk is acceptable.
httpheadertlsreplaysecurity
Reference (http)
Early-Data: 1
Use Early-Data with replay-safe handling and return 425 Too Early when a request must not be processed before replay risk is acceptable.
Common mistakes
- Processing state-changing early data as though it cannot be replayed.
IANA registry: http-fields/field-names
Registry reference: RFC 8470: Using Early Data in HTTP