Patched code sample

import pandas as pd
from typing import Any, Dict

def safe_run_query(df: pd.DataFrame, query: str, query_engine: str = 'numexpr') -> pd.DataFrame:
    """
    Safely executes a query on a Pandas DataFrame.

    Args:
        df: The Pandas DataFrame to query.
        query: The query string.
        query_engine: The query engine to use ('numexpr' or 'pandas').

    Returns:
        The result of the query as a DataFrame.

    Raises:
        ValueError: If the query engine is not supported.
        Exception: If the query execution fails (e.g., due to invalid query).
    """

    if query_engine not in ['numexpr', 'pandas']:
        raise ValueError("Unsupported query engine.  Must be 'numexpr' or 'pandas'.")

    try:
        if query_engine == 'numexpr':
            # Using numexpr is generally safer, but it has its limitations.
            # If numexpr fails, a fallback mechanism to pandas (with restrictions) can be implemented.
            result = df.query(query, engine='numexpr')  # Still use query, but restrict engine.

        elif query_engine == 'pandas':
            # Mitigation: Implement input validation and sanitization here.
            #  Specifically, implement an allow-list or block-list approach to prevent injection attacks.
            #  A robust solution requires detailed analysis of the possible injection vectors.
            #  For example:
            #   1.  Check that query only contains allowed characters (e.g., alphanumeric, basic operators).
            #   2.  Parse the query to ensure it doesn't contain malicious function calls (e.g., os.system).
            #   3.  Limit the length of the query to prevent buffer overflows.
            #   4.  Consider a sandbox environment for executing the pandas query.

            # Placeholder for sanitization (replace with actual implementation):
            sanitized_query = sanitize_query(query)  # Call to sanitization function

            if sanitized_query is not None:
                result = df.query(sanitized_query, engine='python')  # Restrict engine to python, but sanitize

            else:
                raise ValueError("Query failed sanitization.")

        return result

    except Exception as e:
        raise Exception(f"Query execution failed: {e}")

def sanitize_query(query: str) -> str:
    """
    Sanitizes the query string to prevent command injection.

    This is a placeholder and should be replaced with a robust implementation.
    For example:
        1. Check if the query contains potentially dangerous functions (e.g., import, os.system).
        2. Use an allow list of characters and operators.
        3. Implement a parser to analyze the query structure.

    Args:
        query: The query string to sanitize.

    Returns:
        The sanitized query string, or None if sanitization fails.
    """
    # Basic example:  Reject queries containing 'import' or 'os.system'.
    if 'import' in query or 'os.system' in query:
        return None  # Reject query

    # More robust example using a regular expression and allow list

    allowed_characters = r"^[a-zA-Z0-9\s+\-*/().&|<>=!]+$"

    import re
    if not re.match(allowed_characters, query):
        return None

    return query # Return sanitized query