field Registered
Verified 2026-09-18 · registry updated
2026-08-28Transfer-Encoding
Describes the transfer coding applied to the message body, usually chunked.
Transfer-Encoding is hop-by-hop framing: proxies must remove their own coding before forwarding. It is forbidden in HTTP/2 and HTTP/3, and its conflict with Content-Length is the classic request-smuggling vector.
httpheaderframingproxysecurity
Reference (http)
Transfer-Encoding: chunked
Transfer-Encoding is hop-by-hop framing: proxies must remove their own coding before forwarding. It is forbidden in HTTP/2 and HTTP/3, and its conflict with Content-Length is the classic request-smuggling vector.
Common mistakes
- Forwarding both Content-Length and Transfer-Encoding, or sending it on an HTTP/2 request.
IANA registry: http-fields/field-names
Registry reference: RFC 9112, Section 6.1: HTTP Semantics
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