Package Instance

Werkzeug safe_join not safe on Windows
On Python < 3.11 on Windows, `os.path.isabs()` does not catch UNC paths like `//server/share`. Werkzeug's `safe_join()` relies on this check, and so can produce a path that is not safe, potentially allowing unintended access to data. Applications using Python >= 3.11, or not using Windows, are not vulnerable.

Werkzeug safe_join() allows Windows special device names with compound extensions
Werkzeug's `safe_join` function allows path segments with Windows device names that have file extensions or trailing spaces. On Windows, there are special device names such as `CON`, `AUX`, etc that are implicitly present and readable in every directory. Windows still accepts them with any file extension, such as `CON.txt`, or trailing spaces such as `CON `.

This was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the fix failed to account for compound extensions such as `CON.txt.html` or trailing spaces. It also missed some additional special names.

`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.

Werkzeug safe_join() allows Windows special device names
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.

Werkzeug safe_join() allows Windows special device names
Werkzeug's `safe_join` function allows Windows device names as filenames if when preceded by other path segments.

This was previously reported as https://github.com/pallets/werkzeug/security/advisories/GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that `safe_join` accepts paths with multiple segments, such as `example/NUL`.

`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.

Werkzeug possible resource exhaustion when parsing file data in forms
Applications using Werkzeug to parse `multipart/form-data` requests are vulnerable to resource exhaustion. A specially crafted form body can bypass the `Request.max_form_memory_size` setting.


The `Request.max_content_length` setting, as well as resource limits provided by deployment software and platforms, are also available to limit the resources used during a request. This vulnerability does not affect those settings. All three types of limits should be considered and set appropriately when deploying an application.