Patched code sample

Since the specified CVE is not a real one and the actual proprietary source code for n8n is not available for reproduction, the following code represents a standard, robust way to fix the described class of Python sandbox escape vulnerabilities.

The vulnerability typically arises from using `exec()` with an incomplete blocklist, allowing code to access object internals to break out. The fix involves using a dedicated library like `RestrictedPython` that compiles the code in a restricted mode, preventing access to unsafe attributes from the outset.

```python
from RestrictedPython import compile_restricted, safe_globals
from RestrictedPython.PrintCollector import PrintCollector

def execute_fixed_sandboxed_code(untrusted_code: str):
    """
    Executes Python code in a secured, restricted environment using RestrictedPython.

    This function represents a fix for a sandbox escape vulnerability. It uses
    compile_restricted to parse and rewrite the user-provided code, removing or
    disabling access to unsafe attributes (e.g., `__globals__`, `__subclasses__`)
    before execution. This prevents the code from introspecting its way to
    dangerous modules like 'os' or 'sys'.

    Args:
        untrusted_code: A string containing the Python code from a user.

    Returns:
        A string containing the output from print statements in the user's code,
        or an error message if execution fails.
    """
    # A dictionary to hold the local execution environment.
    local_env = {}

    # Use a copy of RestrictedPython's safe global environment.
    # This provides a curated list of safe built-in functions.
    extended_globals = safe_globals.copy()

    # To securely capture output, RestrictedPython uses a `_print_` object.
    # We assign PrintCollector to it, which will store any printed text.
    extended_globals['_print_'] = PrintCollector

    try:
        # This is the core of the fix. The untrusted code is not executed
        # directly. Instead, it's compiled into bytecode in a restricted mode.
        # This compilation step rewrites the code to enforce security rules.
        byte_code = compile_restricted(
            untrusted_code,
            filename='<user_code>',
            mode='exec'
        )

        # The safe, compiled bytecode is executed. It can only access the
        # functions and objects defined in `extended_globals` and `local_env`.
        exec(byte_code, extended_globals, local_env)
        
        # Retrieve the captured output from the PrintCollector.
        # The result of `_print_()` is the collected string.
        output = local_env.get('_print', lambda: "")()
        return output.strip()

    except Exception as e:
        # Catch any compilation or execution errors and return them as a string.
        return f"Execution Error: {e}"