CVE-2026-25904
Overly permissive Deno configuration in mcp-run-python leads to SSRF
The Pydantic-AI MCP Run Python tool configures the Deno sandbox with an overly permissive configuration that allows the underlying Python code to access the localhost interface of the host to perform SSRF attacks. Note - the "mcp-run-python" project is archived and unlikely to receive a fix.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
Overly permissive Deno configuration in mcp-run-python leads to SSRF
The Pydantic-AI MCP Run Python tool configures the Deno sandbox with an overly permissive configuration that allows the underlying Python code to access the localhost interface of the host to perform SSRF attacks. Note - the "mcp-run-python" project is archived and unlikely to receive a fix.
- Record
CVE-2026-25904- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-918
- Updated
- 2026-11-02
EUVDEUVD-2026-6603
The Pydantic-AI MCP Run Python tool configures the Deno sandbox with an overly permissive configuration that allows the underlying Python code to access the localhost interface of the host to perform SSRF attacks. Note - the "mcp-run-python" project is archived and unlikely to receive a fix.
- Record
EUVD-2026-6603- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-6fgp-m6q4-j3q5
MCP Run Python Deno Sandbox Misconfiguration Allows SSRF Attacks via Localhost Access
Impact
Server-Side Request Forgery (SSRF):
A security vulnerability exists in the mcp-run-python tool (specifically within the Pydantic-AI integration) due to an overly permissive Deno sandbox configuration.
The tool configures the Deno runtime—which is intended to isolate the execution of untrusted Python code—with network permissions that include access to the host's loopback interface (localhost). Consequently, malicious Python code executed through the tool can bypass network isolation and send HTTP requests to internal services running on the host machine. This allows attackers to interact with local APIs, databases, or cloud metadata services that should not be accessible from the sandbox.
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 an alternative execution environment that enforces strict network isolation (e.g., blocking all outbound traffic or explicitly denying access to 127.0.0.1/::1).
Workarounds
There are no configuration-based workarounds provided by the package itself. Remediation requires modifying the source code to restrict the Deno permissions (specifically removing or narrowing the --allow-net flag) or moving the execution to a container with no network access.
Resources
- Record
GHSA-6fgp-m6q4-j3q5- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-918
- Updated
- 2026-11-02
NVD
The Pydantic-AI MCP Run Python tool configures the Deno sandbox with an overly permissive configuration that allows the underlying Python code to access the localhost interface of the host to perform SSRF attacks. Note - the "mcp-run-python" project is archived and unlikely to receive a fix.
- Record
CVE-2026-25904- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-918
- Updated
- 2026-11-02
OSVGHSA-6fgp-m6q4-j3q5
MCP Run Python Deno Sandbox Misconfiguration Allows SSRF Attacks via Localhost Access
Impact
Server-Side Request Forgery (SSRF):
A security vulnerability exists in the mcp-run-python tool (specifically within the Pydantic-AI integration) due to an overly permissive Deno sandbox configuration.
The tool configures the Deno runtime—which is intended to isolate the execution of untrusted Python code—with network permissions that include access to the host's loopback interface (localhost). Consequently, malicious Python code executed through the tool can bypass network isolation and send HTTP requests to internal services running on the host machine. This allows attackers to interact with local APIs, databases, or cloud metadata services that should not be accessible from the sandbox.
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 an alternative execution environment that enforces strict network isolation (e.g., blocking all outbound traffic or explicitly denying access to 127.0.0.1/::1).
Workarounds
There are no configuration-based workarounds provided by the package itself. Remediation requires modifying the source code to restrict the Deno permissions (specifically removing or narrowing the --allow-net flag) or moving the execution to a container with no network access.
Resources
- Record
GHSA-6fgp-m6q4-j3q5- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L - Weakness
- CWE-918
- Updated
- 2026-11-02
OSVPYSEC-2026-2627
MCP Run Python Deno Sandbox Misconfiguration Allows SSRF Attacks via Localhost Access
Impact
Server-Side Request Forgery (SSRF):
A security vulnerability exists in the mcp-run-python tool (specifically within the Pydantic-AI integration) due to an overly permissive Deno sandbox configuration.
The tool configures the Deno runtime—which is intended to isolate the execution of untrusted Python code—with network permissions that include access to the host's loopback interface (localhost). Consequently, malicious Python code executed through the tool can bypass network isolation and send HTTP requests to internal services running on the host machine. This allows attackers to interact with local APIs, databases, or cloud metadata services that should not be accessible from the sandbox.
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 an alternative execution environment that enforces strict network isolation (e.g., blocking all outbound traffic or explicitly denying access to 127.0.0.1/::1).
Workarounds
There are no configuration-based workarounds provided by the package itself. Remediation requires modifying the source code to restrict the Deno permissions (specifically removing or narrowing the --allow-net flag) or moving the execution to a container with no network access.
Resources
- Record
PYSEC-2026-2627- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L - Updated
- 2026-11-02
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mcp-run-pythonPyPI |
through 0.0.22 | None known |
mcp-run-pythonPyPI |
through 0.0.22, plus listed versions 0.0.10.0.20.0.200.0.21 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-25904 is a medium vulnerability (CVSS 5.8) in mcp-run-python, published February 9, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.19%, the 8th percentile. No source names a fixed version.