Cardboard boxes are acceptable for frozen products, but purely from a practical perspective. Meaning, it is often impossible to get the product out of the box without thawing the product in order to do so.
In such circumstances, once the product is ready to be thawed and used, the box should be stored in an area of the fridge dedicated for this purpose and away from possibly of cross-contamination. Read more about this in our article on “how to handle foods safely”. And removing the boxes once its possible.