A program using FoundationNetworking in swift-corelibs-foundation is potentially vulnerable to CRLF ( ) injection in URLRequest headers. In this vulnerability, a client can insert one or several CRLF sequences into a URLRequest header value. When that request is sent via URLSession to an HTTP server, the server may interpret the content after the CRLF as extra headers, or even a second request. For example, consider a URLRequest to http://example.com/ with the GET method. Suppose we set the URLRequest header "Foo" to the value "Bar Extra-Header: Added GET /other HTTP/1.1". When this request is sent, it will appear to the server as two requests: GET / HTTP/1.1 Foo: Bar Extra-Header: Added GET /other HTTP/1.1 In this manner, the client is able to inject extra headers and craft an entirely new request to a separate path, despite only making one API call in URLSession. If a developer has total control over the request and its headers, this vulnerability may not pose a threat. However, thi…