GHSA-pfv4-wmph-5gc6

Source

https://github.com/advisories/GHSA-pfv4-wmph-5gc6

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-pfv4-wmph-5gc6/GHSA-pfv4-wmph-5gc6.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-pfv4-wmph-5gc6

Aliases

CVE-2026-25905

Published

2026-02-09T09:30:22Z

Modified

2026-02-12T03:41:18.088234Z

Severity

5.8 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L CVSS Calculator

Summary

MCP Run Python has a Sandbox Escape & Server Takeover Vulnerability

Details

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

Database specific

{
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-12T03:09:38Z",
    "severity": "MODERATE",
    "nvd_published_at": "2026-02-09T09:16:34Z",
    "cwe_ids": [
        "CWE-653"
    ]
}

References

Affected packages

PyPI / mcp-run-python

Package

Name: mcp-run-python; View open source insights on deps.dev
Purl: pkg:pypi/mcp-run-python

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Last affected

0.0.22

Affected versions

0.*

0.0.1

0.0.2

0.0.20

0.0.21

0.0.22

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-pfv4-wmph-5gc6/GHSA-pfv4-wmph-5gc6.json"