mcp-ui-playground

The server generates UIResources with `text/html` content by directly embedding tool input parameters (e.g., `title`, `description`, `name`, `text`, `location`) into HTML strings without proper HTML escaping. This creates a significant Cross-Site Scripting (XSS) vulnerability if any of these inputs originate from untrusted sources (e.g., user prompts to an AI agent that invokes these tools). For example, if a tool's `title` parameter contains `<script>alert('XSS')</script>`, it would be directly rendered and executed in the client's iframe. The `application/vnd.mcp-ui.remote-dom` content type involves sending JavaScript code to the client for dynamic DOM manipulation; while the client is intended to run this in a sandboxed environment, this approach inherently carries higher risk compared to static HTML if client-side sandboxing mechanisms are compromised or misconfigured.