Impact Wreck strips credential headers (Authorization, Cookie, Proxy-Authorization) before following a cross-origin redirect, but the origin check compares hostnames only and ignores scheme and port. As a result, credentials are forwarded intact across same-host port changes and HTTPS-to-HTTP downgrades, allowing a co-tenant on an adjacent port or a network-position attacker capable of forging a redirect to capture bearer tokens, session cookies, and proxy credentials and impersonate the victim against the upstream service. The fix replaces the hostname comparison with a full-origin comparison (scheme, host, and port), aligning the behavior with the WHATWG Fetch same-origin definition used by browsers. Patches Upgrade to >= 18.1.2. Workarounds - Set "redirects: 0" (default) and handle redirects manually with a strict origin check. - Use the "beforeRedirect" hook to inspect the redirect target and abort or strip sensitive headers before the follow-on request.