CVE-2020-26268: In affected versions of TensorFlow the tf.raw_ops.ImmutableConst operation returns a constant tensor created from a memo

A bug in TensorFlow's tf.raw_ops.ImmutableConst operation (a function that creates fixed tensors from memory-mapped files) causes the Python interpreter to crash when the tensor type is not an integer type, because the code tries to write to memory that should be read-only. This crash happens when the file is large enough to contain the tensor data, resulting in a segmentation fault (a critical memory access error).