Vulnerable code sample

import os
import subprocess

def execute_untrusted_code(code):
    """Vulnerable function that demonstrates the security issue."""
    # VULNERABLE: This code is susceptible to command injection
    """
    Executes untrusted Python code within a sandbox.  This version
    demonstrates the vulnerability CVE-2025-49131 by allowing
    unrestricted subprocess calls and file system access from within
    the sandbox.  This is UNSAFE and should NOT be used in production.

    BEFORE version 4.9.11, the sandbox allowed for arbitrary syscalls,
    leading to potential sandbox escapes.  This code mimics that behavior.
    """
    try:
        # Create a temporary file to store the untrusted code.
        with open("temp_code.py", "w") as f:
            f.write(code)

        # Execute the untrusted code using subprocess.
        # BEFORE the fix, no syscall filtering was in place,
        # allowing for arbitrary system calls.  This allows the code
        # to break out of the intended sandbox.
        process = subprocess.Popen(["python", "temp_code.py"],
                                   stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE)
        stdout, stderr = process.communicate()

        # Clean up the temporary file.
        os.remove("temp_code.py")

        return stdout.decode(), stderr.decode()

    except Exception as e:
        return "", str(e)


if __name__ == "__main__":
    # Example of malicious code that reads a sensitive file
    # in the host system (mimicking a sandbox escape).
    malicious_code = """
import os
try:
    # Attempt to read /etc/passwd (or another sensitive file)
    with open("/etc/passwd", "r") as f:
        content = f.read()
    print("Content of /etc/passwd:", content) # Printing to stdout which is captured

    # Create a file outside of the intended sandbox (simulated here by just creating a file)
    with open("evil_file.txt", "w") as f:
        f.write("I escaped the sandbox!")
    print("Sandbox escape successful - wrote to file 'evil_file.txt'")

except Exception as e:
    print("Error during sandbox escape:", str(e))
"""


    stdout, stderr = execute_untrusted_code(malicious_code)

    print("Stdout:", stdout)
    print("Stderr:", stderr)

    #After running the program a file called 'evil_file.txt' is created in the same directory which demostrates how easy
    #it could have been to create a file outside the intended sandbox boundaries.  The printing of the content of /etc/passwd
    #is also another example of how sensitive information could have been compromised.