undici is an HTTP client for Node.js. In versions 7.0.0 through 7.30.1 and 8.0.0 through 8.12.3, the redirect interceptor strips sensitive headers such as Authorization, Cookie, Proxy-Authorization, and Host when a request is redirected to a different origin, but when request headers are supplied as an array of name and value tuples (a valid documented input, for example from Object.entries), the redirect handler misreads them as a flat list so the header names never match and the sensitive headers are not removed. If a header-normalizing interceptor such as cache or deduplicate is composed outside the redirect interceptor, it then serializes the retained headers onto the cross-origin reques