Patched code sample

import ast

def process_configuration(config_string: str):
    """
    Processes a configuration string from an untrusted source.

    Vulnerability Fix for CVE-2025-33184:
    A hypothetical vulnerable version of this function might have used `eval()`
    to parse the incoming 'config_string'. Using `eval()` on untrusted input
    is a classic code injection vulnerability, as it would execute any valid
    Python code passed to it. For example, an attacker could provide the string
    "__import__('os').system('malicious_command')".

    The fix replaces the dangerous `eval()` call with `ast.literal_eval()`.
    This function is a safe alternative that only evaluates strings containing
    Python literals: strings, numbers, tuples, lists, dictionaries, booleans,
    and None. It explicitly prevents the execution of arbitrary code, function
    calls, or complex expressions, thereby mitigating the code injection risk.
    """
    try:
        # SAFE: Use ast.literal_eval to safely parse a string containing a Python literal.
        # This prevents the execution of arbitrary code by disallowing function calls,
        # attribute access, and other operations beyond literal structures.
        config_data = ast.literal_eval(config_string)

        # Example of further processing on the now-safe data object.
        if isinstance(config_data, dict):
            print(f"Configuration loaded successfully: {config_data.get('setting')}")
            # ... logic to apply the configuration settings ...
        else:
            print("Warning: Configuration is not in the expected dictionary format.")

        return config_data

    except (ValueError, TypeError, SyntaxError, MemoryError, RecursionError) as e:
        # Handle cases where the input string is not a valid Python literal.
        # This catches malformed strings as well as malicious attempts that
        # ast.literal_eval rejects.
        print(f"Error: Could not process invalid or malicious configuration string. Details: {e}")
        return None

# # --- Example Usage Demonstrating Safety ---
#
# # 1. Benign and valid configuration string (SAFE)
# safe_config = "{'setting': 'mode_a', 'value': 123}"
# process_configuration(safe_config)
#
# # 2. Malicious string attempting code injection (REJECTED)
# # The vulnerable eval() would execute this, but literal_eval() will raise an error.
# malicious_config = "__import__('os').system('echo pwned')"
# process_configuration(malicious_config)
#
# # 3. Malformed string (REJECTED)
# malformed_config = "{'setting': 'mode_b" # Missing closing quote and brace
# process_configuration(malformed_config)