GHSA-36hh-x5p5-jgc8

Description

### Impact The two parsers resolved duplicates inconsistently and silently: - `Content.disposition()` retained the last occurrence of each parameter. - `Content.type()` retained the first occurrence of charset and boundary. Either behavior creates a parameter-smuggling primitive when another component in the request-processing chain (a WAF, reverse proxy, security filter, or alternate parser) resolves duplicates the opposite way. The primary attack vector is upload filename allowlist bypass: `Content-Disposition: form-data; name="file"; filename="safe.txt"; filename="shell.php"` ### Patches The issue has been patched in 6.0.2. ### Workarounds Pre or post validate headers looking for duplicates. ### Resources - [RFC 6266 §4.1 — Content-Disposition syntax](https://www.rfc-editor.org/rfc/rfc6266#section-4.1) - [RFC 7231 §3.1.1.1 — Content-Type syntax](https://www.rfc-editor.org/rfc/rfc7231#section-3.1.1.1) - [RFC 7230 §3.2.6 — token character set](https://www.rfc-editor.org/rfc/rfc7230#section-3.2.6)