cpp-httplib is a C++ header-only HTTP/HTTPS library. Prior to 0.51.0, create_redirect_client() removes Host, Proxy-Authorization, and Authorization headers when following a cross-origin 301, 302, 307, or 308 redirect but leaves Cookie headers attached. detail::redirect() copies the request for those redirect codes, so cookies supplied directly or through default_headers_ are sent to the redirect target. An attacker who controls a redirect response, or a network position for a non-HTTPS origin, can receive session cookies intended for the original origin. A 303 redirect is not affected because that path clears all request headers. This issue is fixed in version 0.51.0.