GHSA-hgf8-39gv-g3f2: Werkzeug safe_join() allows Windows special device names

• Source: GitHub Global Advisories

Werkzeug's `safe_join` function allows Windows special device names, leading to indefinite hangs when serving files on Windows.

Werkzeug's `safe_join` function allows path segments with Windows device names. On Windows, there are special device names such as `CON`, `AUX`, etc that are implicitly present and readable in every directory. `send_from_directory` uses `safe_join` to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely.