A vulnerability in actix-http's HTTP/1 chunked decoder allows request smuggling via malformed chunked request trailers. The decoder incorrectly accepts a bare line feed after the final chunk as the start of a trailer instead of rejecting the request. This flaw can cause the decoder to consume the next request's headers as trailer data, potentially bypassing access controls enforced by proxies or web application firewalls. The issue is fixed in actix-http version 3.20.2.