Seems like your fix[1] for this is a bit fast. You are already importing `path` in that file. Also, you can do this with just one `path.relative`. Lastly, the url package method you are using is deprecated[2].
A simpler fix might be to canonicalize (i.e. no "..") the public folder path and the requested file path and then ensure the public path is a prefix of the other.
[1] https://github.com/remoteinterview/zero/commit/b4af5325c388e... [2] https://nodejs.org/api/url.html#url_legacy_url_api