Patched code sample

# This code represents a hypothetical fix in a file like fickling/security.py
#
# The original vulnerability was that 'pty' was missing from this set,
# allowing pickles that used pty.spawn() to be incorrectly marked as safe.
#
# The fix is to add 'pty' to the set of known unsafe module imports.

import sys

# A frozenset of known unsafe module imports that can be used for RCE.
# The addition of 'pty' to this set is the fix for CVE-2025-67748.
_UNSAFE_IMPORTS = frozenset(
    [
        "__builtin__",
        "__main__",
        "builtins",
        "copy_reg",
        "ctypes",
        "dill",
        "marshal",
        "modules",
        "os",
        "pickle",
        "pty",  # This line is the fix.
        "shelve",
        "shutil",
        "subprocess",
        "sys",
        "system",
        "torch",
        "winreg",
        "_winreg",
        "zipfile",
        "zipimport",
    ]
)

def is_import_safe(module_name: str) -> bool:
    """
    Checks if a module is in the block list of unsafe imports.
    """
    # In a real scenario, this might involve more complex checks,
    # but the core logic relies on the _UNSAFE_IMPORTS set.
    return module_name not in _UNSAFE_IMPORTS

if __name__ == "__main__":
    # Demonstration of the fix
    vulnerable_import = "pty"
    another_unsafe_import = "os"
    safe_import = "math"

    print(f"Checking module '{vulnerable_import}'...")
    if is_import_safe(vulnerable_import):
        print(f"Result: '{vulnerable_import}' is considered safe. (This would be the VULNERABLE behavior)")
    else:
        print(f"Result: '{vulnerable_import}' is correctly flagged as UNSAFE. (This is the FIXED behavior)")

    print("-" * 20)

    print(f"Checking module '{another_unsafe_import}'...")
    if is_import_safe(another_unsafe_import):
        print(f"Result: '{another_unsafe_import}' is considered safe.")
    else:
        print(f"Result: '{another_unsafe_import}' is correctly flagged as UNSAFE.")

    print("-" * 20)

    print(f"Checking module '{safe_import}'...")
    if is_import_safe(safe_import):
        print(f"Result: '{safe_import}' is correctly flagged as SAFE.")
    else:
        print(f"Result: '{safe_import}' is considered unsafe.")