Patched code sample

import ast

class JobWorkflowExecutor:
    """
    A conceptual representation of the class from the CVE description.
    """
    class _SecureAstValidator(ast.NodeVisitor):
        """
        This validator implements the fix by thoroughly inspecting the code's
        Abstract Syntax Tree (AST) for forbidden patterns. The original vulnerability
        arose from insufficient validation.
        """
        FORBIDDEN_MODULES = {'os', 'sys', 'subprocess', 'shutil', 'ctypes'}
        FORBIDDEN_BUILTINS = {'__import__', 'eval', 'exec', 'open'}
        FORBIDDEN_ATTRIBUTES = {
            'system', 'popen', 'spawn', 'call', 'run',  # Common os/subprocess functions
            '__subclasses__', '__globals__', '__code__' # Introspection/escape attributes
        }

        def visit_Import(self, node: ast.Import):
            """
            Prevents 'import os' and other dangerous modules.
            """
            for alias in node.names:
                if alias.name in self.FORBIDDEN_MODULES:
                    raise PermissionError(f"Import of forbidden module '{alias.name}' is not allowed.")
            self.generic_visit(node)

        def visit_ImportFrom(self, node: ast.ImportFrom):
            """
            Prevents 'from os import system' and other dangerous imports.
            """
            if node.module and node.module in self.FORBIDDEN_MODULES:
                raise PermissionError(f"Import from forbidden module '{node.module}' is not allowed.")
            self.generic_visit(node)

        def visit_Call(self, node: ast.Call):
            """
            Prevents calls to dangerous built-in functions like __import__('os').
            """
            if isinstance(node.func, ast.Name) and node.func.id in self.FORBIDDEN_BUILTINS:
                raise PermissionError(f"Call to forbidden function '{node.func.id}' is not allowed.")
            self.generic_visit(node)

        def visit_Attribute(self, node: ast.Attribute):
            """
            Prevents access to dangerous attributes like '.system'.
            This stops calls like 'x.system()' even if 'os' was imported indirectly.
            """
            if node.attr in self.FORBIDDEN_ATTRIBUTES:
                raise PermissionError(f"Access to forbidden attribute '{node.attr}' is not allowed.")
            self.generic_visit(node)

    def _exec_inline_python(self, code_string: str):
        """
        This is the fixed version of the vulnerable method. It uses the
        _SecureAstValidator to prevent malicious code from being executed.
        """
        try:
            # Step 1: Parse the untrusted code string into an AST.
            tree = ast.parse(code_string)

            # Step 2: Traverse the AST with the secure validator. This is the fix.
            # An exception is raised if any forbidden pattern is found.
            validator = self._SecureAstValidator()
            validator.visit(tree)

            # Step 3: If validation passes, execution in a sandboxed environment
            # would occur here. The vulnerability is patched because the validation
            # step will block malicious payloads before they can be executed.
            pass

        except (PermissionError, SyntaxError) as e:
            # The vulnerability is fixed because malicious code will raise an
            # exception here, preventing it from ever reaching an execution engine.
            # In a real application, this would be logged and handled.
            raise ValueError(f"Code validation failed: {e}") from e