Sign in Sign up
JA · EN · FR
SecPulse
Categories
CVE-2026-25905

Vulnerability in mcp-run-python (CVE-2026-25905)

Summary

Vulnerability in mcp-run-python (CVE-2026-25905). Risk of unauthorized operations or information disclosure. Exploitable via runPython.

Original description

The description as published by the source.

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

T…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-25905 has been found in mcp-run-python.
Attackers can target a specific entry point like runPython over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "mcp-run-python CVE-2026-25905" on the vendor's site.

CVE-2026-25905 (mcp-run-python) — CWE-653
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: runPython / runPythonAsync
Workaround: There are no configuration-based workarounds.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-653) exists in mcp-run-python. Attackers reach the vulnerable code path via runPython without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of mcp-run-python. Attack surface: runPython / runPythonAsync.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Workaround: There are no configuration-based workarounds.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'mcp-run-python' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'mcp-run-python' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で mcp-run-python を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply temporary workaround mitigate 
    There are no configuration-based workarounds.

    パッチが適用されるまでの応急処置として、There are no configuration-based workarounds. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

PyPI mcp-run-python
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.0.22"}]}]

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details