FWIW, this segfaults CPython in 2 lines:

  import ctypes
  ctypes.cast(1, ctypes.py_object)

Interestingly, this works:

  import ctypes, gc
  x = 22
  _id = id(x)
  del x
  gc.collect()
  y = ctypes.cast(_id, ctypes.py_object).value
  assert y == 22