{"id":"CVE-2026-81096","title":"ToolUniverse ran caller-supplied Python inside a sandbox that could be escaped, on a server that required no authentication","summary":"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 fo…","severity":"critical","cvss":10,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","cwe":["CWE-94"],"published":"2026-08-27","updated":"2026-09-23","sourceUpdated":"2026-09-23T17:17:42.553","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81096","references":[{"url":"https://github.com/mims-harvard/ToolUniverse","label":"disclosure@vulncheck.com"},{"url":"https://github.com/mims-harvard/ToolUniverse/pull/251","label":"disclosure@vulncheck.com"},{"url":"https://github.com/mims-harvard/ToolUniverse/security/advisories/GHSA-pxwq-22vf-87fm","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/tooluniverse-through-1.2.6-unauthenticated-remote-code-execution-via-python-code-executor-sandbox-escape","label":"disclosure@vulncheck.com"}],"tags":["nvd"],"epss":0.00574,"epssPercentile":0.46142,"ingestedAt":"2026-09-23T17:28:14.806Z","slug":"CVE-2026-81096","body":"## Overview\n\nToolUniverse 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":55,"depthScoreParts":{"impact":55,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}