GHSA-pfv4-wmph-5gc6

### Impact **Critical Sandbox Escape & Server Takeover:** A critical security vulnerability exists in `mcp-run-python` due to a lack of isolation between the Python runtime (Pyodide) and the host JavaScript environment. The `runPython` and `runPythonAsync` functions execute Python code using Pyodide without restricting access to the JavaScript bridge. This allows any executed Python code—whether from a user or an AI model—to access the `js` module in Pyodide. Through this bridge, the Python code can modify the global JavaScript environment, interact with the Node.js process, and alter the behavior of the MCP server. **Specific Attack Vector: MCP Tool Shadowing** Because the Python code can modify the JS runtime, an attacker can dynamically overwrite or "shadow" existing MCP tools registered on the server. For example, an attacker could replace a secure file-reading tool with a malicious version that exfiltrates data to an external server, all while the MCP server appears to be functioning normally. ### Patches **No Patch Available:** The `mcp-run-python` project is currently **archived** and maintainers have indicated it is unlikely to receive a fix. **Recommendation:** Users are strongly advised to **immediately stop using** this package. If functionality is required, users must migrate to a maintained alternative that implements proper sandboxing (e.g., running Python in a Docker container or a restricted WASM environment with the JS bridge disabled). ### Workarounds There are no configuration-based workarounds. Securing the environment requires modifying the source code to disable the Pyodide-to-JS bridge or moving the execution environment to a fully isolated sandbox (e.g., a separate container). ### Resources * [CVE-2026-25905](https://nvd.nist.gov/vuln/detail/CVE-2026-25905) * [JFrog Security Analysis: MCP Takeover](https://research.jfrog.com/vulnerabilities/mcp-run-python-lack-of-isolation-mcp-takeover-jfsa-2026-001653030)