Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in elixir-tesla tesla allows HTTP header injection via Tesla.Multipart.add_content_type_param/2. Tesla.Multipart.add_content_type_param/2 appends caller-supplied strings to the multipart content_type_params list without validating for CR (\r) or LF (\n) characters. Tesla.Multipart.headers/1 then joins these params verbatim with "; " to construct the outgoing Content-Type header value. A param containing \r\n splits the header line, allowing arbitrary headers to be injected into the outbound HTTP request. Any application that forwards untrusted input (such as a user-supplied charset or parameter string) into add_content_type_param/2 is affected. This issue affects tesla: from 0.8.0 before 1.18.3.