Vulnerabilities in pkg:pypi/mcp-run-python

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-pfv4-wmph-5gc6",
  "modified" : "2026-02-12T03:09:38Z",
  "published" : "2026-02-09T09:30:22Z",
  "aliases" : [ "CVE-2026-25905" ],
  "summary" : "MCP Run Python has a Sandbox Escape & Server Takeover Vulnerability",
  "details" : "### Impact\n**Critical Sandbox Escape & Server Takeover:**\nA critical security vulnerability exists in `mcp-run-python` due to a lack of isolation between the Python runtime (Pyodide) and the host JavaScript environment.\n\nThe `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.\n\n**Specific Attack Vector: MCP Tool Shadowing**\nBecause 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.\n\n### Patches\n**No Patch Available:**\nThe `mcp-run-python` project is currently **archived** and maintainers have indicated it is unlikely to receive a fix.\n\n**Recommendation:**\nUsers are strongly advised to **immediately stop using** this package.\nIf 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).\n\n### Workarounds\nThere 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).\n\n### Resources\n* [CVE-2026-25905](https://nvd.nist.gov/vuln/detail/CVE-2026-25905)\n* [JFrog Security Analysis: MCP Takeover](https://research.jfrog.com/vulnerabilities/mcp-run-python-lack-of-isolation-mcp-takeover-jfsa-2026-001653030)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "mcp-run-python"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.0.22"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-25905"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pydantic/mcp-run-python"
  }, {
    "type" : "WEB",
    "url" : "https://research.jfrog.com/vulnerabilities/mcp-run-python-lack-of-isolation-mcp-takeover-jfsa-2026-001653030"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-653" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-12T03:09:38Z",
    "nvd_published_at" : "2026-02-09T09:16:34Z"
  }
}