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CVSS 10.0CVSS 10.0 · CRITICAL

CVE-2026-81096Unauthenticated RCE in ToolUniverse via sandbox escape

ToolUniverse ran caller-supplied Python inside a sandbox that could be escaped, on a server that required no authentication. The executor behind the python_code_executor tool, in python_executor_tool.py, inspected the submitted source for a denied list of attribute names and calls but left the attribute-lookup builtins available and did not stop a dunder attribute reached through a string lookup or through a module already permitted, so a caller could walk from a literal's class to its base and enumerate subclasses to obtain a reference to the process and subprocess modules. A per-call argument also let the caller widen the import allow-list before the inspection ran. The HTTP and MCP servers in http_api_server.py and smcp_server.py bound to every interface with debugging enabled and no authentication, so any caller able to reach the port executed code as the server process. Version 1.3.0 adds bearer-token authentication, defaults the bind address to loopback, and hardens the attribute checks.

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Analysis

ToolUniverse permite la ejecución remota de código (RCE) sin autenticación mediante un escape de su sandbox de Python. Los atacantes pueden evadir las restricciones de inspección para acceder a módulos del sistema y ejecutar comandos arbitrarios en el servidor. La vulnerabilidad es crítica debido a que el servicio expone sus interfaces de red por defecto con la depuración habilitada.

Relevant roles

PythonBackendaiIAciberseguridad

Severity

Score: 10.0(CRITICAL)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
AV: NETWORK
AC: LOW
PR: NONE
UI: NONE
S: CHANGED
C: HIGH
I: HIGH
A: HIGH
Weakness (CWE): CWE-94

EPSS

No EPSS score yet (CVE may be too fresh).

Technical description

ToolUniverse ran caller-supplied Python inside a sandbox that could be escaped, on a server that required no authentication. The executor behind the python_code_executor tool, in python_executor_tool.py, inspected the submitted source for a denied list of attribute names and calls but left the attribute-lookup builtins available and did not stop a dunder attribute reached through a string lookup or through a module already permitted, so a caller could walk from a literal's class to its base and enumerate subclasses to obtain a reference to the process and subprocess modules. A per-call argument also let the caller widen the import allow-list before the inspection ran. The HTTP and MCP servers in http_api_server.py and smcp_server.py bound to every interface with debugging enabled and no authentication, so any caller able to reach the port executed code as the server process. Version 1.3.0 adds bearer-token authentication, defaults the bind address to loopback, and hardens the attribute checks.

Published: 8/27/2026, 5:20:51 PM
Last modified: 8/27/2026, 5:20:51 PM

References

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