Home/CVE/The Python code being run by 'runPython' or 'runPythonAsync' is not isolated from the rest of the JS code, allowing any
CVE

CVE-2026-25905

The Python code being run by 'runPython' or 'runPythonAsync' is not isolated from the rest of the JS code, allowing any

The Python code being run by 'runPython' or 'runPythonAsync' is not isolated from the rest of the JS code, allowing any Python code to use the Pyodide APIs to modify the JS environment. This may result in an attacker hijacking the MCP server - for malicious purposes including MCP tool shadowing. Note - the "mcp-run-python" project is archived and unlikely to receive a fix.

MEDIUM · CVSS 5.8 EPSS 0.00013
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-653Improper Isolation or Compartmentalization
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
PyPI mcp-run-python MODERATE
▣

Scoring & Timeline

5.8
MEDIUM · CVSS v3.1 · reefs@jfrog.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD09 Feb 2026 · 09:16 AM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://research.jfrog.com/vulnerabilities/mcp-run-python-lack-of-isolation-mcp-takeover-jfsa-2026-001653030/
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