CLTE-SMUGGLED-GET-TE-TRAILING-SPACE

What it does

This is a variant of SMUG-CLTE-SMUGGLED-GET where the Transfer-Encoding value includes a trailing space (chunked␠).

Some components treat this as invalid and fall back to Content-Length; others trim and treat it as chunked. In a multi-hop chain, that parsing differential can enable CL.TE request smuggling.

What it sends

POST / HTTP/1.1\r\n
Host: localhost:8080\r\n
Content-Length: 45\r\n
Transfer-Encoding: chunked \r\n
\r\n
0\r\n
\r\n
GET / HTTP/1.1\r\n
Host: localhost:8080\r\n
\r\n

What the RFC says

“A server MAY reject a request that contains both Content-Length and Transfer-Encoding… Regardless, the server MUST close the connection after responding to such a request.” — RFC 9112 §6.1

Why it matters

TE value normalization is a common hardening gap. If one hop trims and another does not, the chain can disagree about message framing and interpret the embedded GET as a second request.

Verdicts

• Pass: The server rejects with 400, or closes the connection.
• Fail: Multiple HTTP responses are observed (embedded GET likely executed).
• Fail: The server accepts and keeps the connection open (MUST-close violated), even if no extra response is observed.

Sources

• RFC 9112 §6.1