CVE-2025-25296: Label Studio Cross-Site Scripting via upload-example Endpoint

The /projects/upload-example endpoint renders a labeling config passed in the label_config query parameter. It accepts a GET request and renders inline task data from the config as HTML without sanitizing it.

An attacker embeds script in the task data, URL-encodes the config, and sends the link to a victim. The script runs when the page loads. Label Studio ships a Content Security Policy, but only in report-only mode, so it does not block execution. Label Studio 1.16.0 fixes the issue.