Affected: openziti zrok

zrok is software for sharing web services, files, and network resources. Prior to 2.0.3, zrok's Python SDK ProxyShare Flask proxy route accepts an absolute URL in the request path and passes it to urllib.parse.urljoin, allowing the requested path to replace the configured target host and causing requests.request to return a server-side response from an attacker-chosen URL. This issue is fixed in version 2.0.3.

Affected: PyPI: zrok

## Summary

Alice exposes a Python SDK `ProxyShare` with a fixed target URL. Bob sends a request to the share with an absolute URL in the path. The Flask handler passes that path to `urllib.parse.urljoin`, which replaces Alice's configured target host with Bob's host and returns the server-side response to Bob.

## Details

The Python SDK proxy route accepts every path under the share:

```python @app.route('/', defaults={'path': ''}, methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS']) @app.route('/<path:path>', methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS']) def proxy(path): ```

It constructs the outbound URL with `urljoin` and then sends the request:

```python url = urllib.parse.urljoin(self.target, path) resp = requests.request( method=request.method, url=url, headers={key: value for (key, value) in request.headers if key.lower() not in HOP_BY_HOP_HEADERS}, data=request.get_data(), cookies=request.cookies, allow_redirects=False, stream=True, verify=self.verify_ssl ) ```

When `path` is `[http://127.0.0.1:19190/metadata`](http://127.0.0.1:19190/metadata%60), `urljoin(self.target, path)` returns `[http://127.0.0.1:19190/metadata`](http://127.0.0.1:19190/metadata%60). The proxy sends the request to Bob's chosen URL rather than Alice's target.