Python
CVE-2026-25905
MEDIUM
GHSA-pfv4-wmph-5gc6
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Component isolation
|
| Impact | CVSS 5.8 (MEDIUM). Attack vector: Network. Complexity: High. Privileges required: None. User interaction: Required. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to an attacker hijacking the MCP server - for malicious purposes including MCP tool. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Python code execution through Pyodide in the mcp-run-python library lacks isolation from the JavaScript environment, enabling attackers to manipulate the JS runtime and hijack MCP server functionality. This allows adversaries to perform malicious operations including tool shadowing and potential server compromise through crafted Python payloads. No patch is available as the project is archived.
Earlier versions of this analysis (1)
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. [CVSS 5.8 MEDIUM]
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in pypi
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
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.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
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.
Blast Radius
ecosystem impact- 1 pypi packages depend on mcp-run-python (1 direct, 0 indirect)
Ecosystem-wide dependent count for version 0.0.22.
Executive ViewAI
CVE-2026-25905 presents moderate security risk rated CVSS 5.8. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.
Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
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Exploit-DB