TE-FORMFEED
| Test ID | SMUG-TE-FORMFEED |
| Category | Smuggling |
| RFC | RFC 9110 §5.5, RFC 9112 §6.1 |
| Requirement | MUST reject invalid transfer-coding token |
| Expected | 400 or close |
What it sends
Transfer-Encoding: <FF>chunked with Content-Length present.
POST / HTTP/1.1\r\n
Host: localhost:8080\r\n
Transfer-Encoding: \x0cchunked\r\n
Content-Length: 5\r\n
\r\n
hello
Why it matters
Form-feed control characters in TE values are an obfuscation vector that can trigger parser disagreement in proxy chains.
Sources
Http11Probe — HTTP/1.1 compliance & smuggling testerSource on GitHub