Patched code sample

import ast
import os

# The vulnerability CVE-2025-23298 is not a real CVE as of this date.
# This code provides a hypothetical example of a fix for the described
# vulnerability type: a code injection issue in a Python dependency.
#
# The vulnerability often stems from using insecure functions like eval()
# on untrusted input, which can come from configuration files, data files,
# or network requests. An attacker could craft this input to execute
# arbitrary code.
#
# The fix is to replace the insecure function with a safe alternative.
# In this case, ast.literal_eval is used, which can safely evaluate a
# string containing a Python literal (strings, numbers, tuples, lists,
# dicts, booleans, and None) but does not execute arbitrary code.

# ---------------- CONTEXT: VULNERABLE CODE (FOR ILLUSTRATION) ----------------
#
# This function would be vulnerable if it existed.
#
# def load_and_process_config_vulnerable(config_string: str):
#     """
#     VULNERABLE: Uses eval() on an input string, allowing arbitrary code execution.
#     An attacker could provide a string like:
#     "__import__('os').system('echo Malicious code was executed!')"
#     """
#     print(f"VULNERABLE: Evaluating string: '{config_string}'")
#     return eval(config_string)
#
# -----------------------------------------------------------------------------


# -------------------------- FIXED CODE IMPLEMENTATION --------------------------

def load_and_process_config_fixed(config_string: str):
    """
    FIXED: Uses ast.literal_eval() to safely parse the input string.
    This function only evaluates simple Python literals (dict, list, string, etc.)
    and will raise an exception for any other code, preventing code injection.
    """
    print(f"FIXED: Safely parsing string: '{config_string}'")
    try:
        # ast.literal_eval is the key to the fix. It parses data without
        # executing code.
        parsed_config = ast.literal_eval(config_string)
        
        # Additional type checking can add another layer of security.
        if not isinstance(parsed_config, dict):
            print("Error: Parsed configuration is not a dictionary.")
            return None
            
        return parsed_config
    except (ValueError, SyntaxError, MemoryError, TypeError) as e:
        # If the string is not a valid literal (e.g., contains code),
        # an exception is raised, and the attack is thwarted.
        print(f"SAFE: Blocked potentially malicious input. Error: {e}")
        return None

def main():
    """
    Demonstrates that the fixed function correctly handles both
    legitimate and malicious input strings.
    """
    # 1. A legitimate configuration string (safe)
    safe_config_str = "{'model_name': 'transformer-v1', 'layers': 4, 'enabled': True}"
    
    # 2. A malicious string attempting code injection
    malicious_config_str = "__import__('os').system('echo Malicious code executed!')"
    
    print("--- DEMONSTRATING THE FIX ---")
    
    print("\n[1] Processing a legitimate configuration...")
    result_safe = load_and_process_config_fixed(safe_config_str)
    if result_safe:
        print(f"Successfully and safely parsed config: {result_safe}")
        # Application would continue processing the safe config dict here...
        
    print("\n" + "="*40 + "\n")
    
    print("[2] Processing a malicious configuration string...")
    result_malicious = load_and_process_config_fixed(malicious_config_str)
    if not result_malicious:
        print("The malicious payload was successfully blocked by the fix.")

if __name__ == "__main__":
    main()