CVE-2026-61438 — 脆弱性インテリジェンス
MervinPraison — praisonai
公表日:
- CVSS
- 7
- CISA KEV
- 未掲載（悪用がないことを意味しません）
情報源の原文（翻訳ではありません）
PraisonAI vulnerable to Remote Code Execution via Broken AST Sandbox
### Summary
JobWorkflowExecutor._exec_inline_python() is designed to safely execute inline Python expressions from YAML workflow script: steps using AST validation. The function claims to block dangerous operations by (a) checking all AST nodes against an allowlist, and (b) providing a __builtins__ whitelist that omits __import__, exec, eval, and open.
The sandbox is broken. The module import allowlist (allowed_modules) explicitly includes 'os', and the AST allowlist permits ast.Import, ast.ImportFrom, ast.Call, and ast.Attribute nodes. This means the following malicious workflow script: step passes all AST validation checks and executes without error.
Attack Scenario
Attacker creates or contributes a YAML workflow file (type: job) with a script: step containing import os; os.system(...).
A user or CI pipeline with PRAISONAI_ALLOW_JOB_WORKFLOWS=true executes the workflow via praisonai workflow run malicious.yaml.
Arbitrary OS commands execute with the privileges of the calling process.
This is particularly dangerous in multi-tenant or CI environments where YAML workflows may originate from untrusted sources (e.g., downloaded templates, shared repositories, AI-generated workflows).
### PoC
_Complete instructions, including specific configuration details, to reproduce the vulnerability._
### Impact
Root Cause — Lines 364–372:
pythonallowed_modules = {'os', 'datetime', 'time', 'json', 'math', 're', 'collections', 'itertools'}
if isinstance(node, ast.Import):
for alias in node.names:
if alias.name.split('.')[0] not in allowed_modules:
return {"ok": False, "error": f"Import of '{alias.name}' not allowed..."}
os is trusted because it is commonly used for path operations (os.path, os.getcwd). However, os.system(), os.popen(), os.execvp(), os.spawn*(), and os._exit() are all accessible once the module is imported, none of which are individually blocked.
The __builtins__ restriction (blocking __import__) is irrelevant because the code uses a real import statement processed by the Python bytecode compiler — not a __import__() call.
Proof-of-Concept validation (static — no remote network call made):
pythonimport ast
_ALLOWED_NODES = (
ast.Expression, ast.BoolOp, ast.BinOp, ast.UnaryOp, ast.Compare,
ast.IfExp, ast.Constant, ast.Name, ast.Load, ast.Store, ast.Subscript,
ast.List, ast.Tuple, ast.Dict, ast.Set,
ast.And, ast.Or, ast.Not, ast.Eq, ast.NotEq, ast.Lt, ast.LtE,
ast.Gt, ast.GtE, ast.In, ast.NotIn, ast.Add, ast.Sub, ast.Mult,
ast.Div, ast.Mod, ast.FloorDiv, ast.USub, ast.UAdd,
ast.Call, ast.Attribute, ast.keyword, ast.Starred,
ast.Module, ast.Assign, ast.Import, ast.ImportFrom, ast.alias,
)
allowed_modules = {'os', 'datetime', 'time', 'json', 'math', 're', 'collections', 'itertools'}
malicious = "import os\nresult = os.system('id')"
tree = ast.parse(malicious, mode="exec")
all_pass = True
for node in ast.walk(tree):
if not isinstance(node, _ALLOWED_NODES):
print(f"BLOCKED: {type(node).__name__}")
all_pass = False
if isinstance(node, ast.Import):
for alias in node.names:
if alias.name.split('.')[0] not in allowed_modules:
print(f"IMPORT BLOCKED: {alias.name}")
all_pass = False
print("SANDBOX BYPASSED" if all_pass else "sandbox holds")
# Output: SANDBOX BYPASSED
Recommended Fix
Remove 'os' from allowed_modules and replace it with only the safe submodule: 'os.path'. Then validate that the imported name is specifically os.path, not os:
python# BEFORE (vulnerable)
allowed_modules = {'os', 'datetime', 'time', 'json', 'math', 're', 'collections', 'itertools'}
# AFTER (safe)
allowed_modules = {'datetime', 'time', 'json', 'math', 're', 'collections', 'itertools', 'pathlib'}
# If os.path is needed, handle it explicitly:
if isinstance(node, ast.ImportFrom):
if node.module == 'os.path':
pass # allow 'from os.path import join, exists' only
elif node.module and node.module.split('.')[0] not in allowed_modules:
return {"ok": False, "error": f"Import of '{node.module}' not allowed."}
Additionally, block ast.Import of os entirely, and consider also removing re (which can be used for ReDoS/CPU exhaustion) and collections (which can be used to reach __subclasses__-style gadgets).