CORS origin validation accepts the null origin in Gradio

Gradio is an open-source Python package designed for quick prototyping. This vulnerability relates to **CORS origin validation accepting a null origin**. When a Gradio server is deployed locally, the `localhost_aliases` variable includes "null" as a valid origin. This allows attackers to make unauthorized requests from sandboxed iframes or other sources with a null origin, potentially leading to data theft, such as user authentication tokens or uploaded files. This impacts users running Gradio locally, especially those using basic authentication. Users are advised to upgrade to `gradio>=5.0` to address this issue. As a workaround, users can manually modify the `localhost_aliases` list in their local Gradio deployment to exclude "null" as a valid origin. By removing this value, the Gradio server will no longer accept requests from sandboxed iframes or sources with a null origin, mitigating the potential for exploitation.