CVE-2026-111756

### Summary follow-redirects removes sensitive credential headers (Authorization, Proxy-Authorization, Cookie, and any caller-declared `sensitiveHeaders`) before following a redirect that crosses to a different host or downgrades to a less secure protocol. The removal routine iterates the caller's headers container with `for...in` and matches header names against a filter. This assumes the headers container is a plain object keyed by header names. Node's underlying `http.request`, which follow-redirects is a drop-in replacement for, also accepts headers as an alternating array of names and values. For an array, `for...in` yields the numeric indices `"0"`, `"1"`, `"2"` and so on, which never match a header-name filter, so nothing is removed. An application that sends array-form headers and follows an attacker-controlled cross-origin redirect therefore forwards its Authorization, Cookie, and Proxy-Authorization headers verbatim to the attacker-controlled destination, with no error or warning. The `sensitiveHeaders` option added to fix CVE-2026-40895 / GHSA-r4q5-vmmm-2653 is equally ineffective, because it relies on the same helper. This is an unauthenticated confidentiality vulnerability: any remote server the victim application contacts can harvest the victim's credential headers by responding with a cross-origin redirect. ### Details The cross-origin credential-stripping control is implemented by `removeMatchingHeaders(regex, headers)` at `index.js:630-640`: ```js function removeMatchingHeaders(regex, headers) { var lastValue; for (var header in headers) { // for...in over an ARRAY yields "0","1","2"... if (regex.test(header)) { // the header-name filter never matches a numeric index lastValue = headers[header]; delete headers[header]; } } return (lastValue === null || typeof lastValue === "undefined") ? undefined : String(lastValue).trim(); } ``` It is invoked from `_processResponse` for three purposes, all wit