Preheat your oven to 350°F (175°C).
Prepare the cake mix according to package instructions.
Pour the batter into a greased 9x13 inch baking pan.
Bake for 28-30 minutes, or until a toothpick inserted in the center comes out clean.
Remove the cake from the oven and let it cool for 10 minutes.
Poke holes in the cake using the end of a wooden spoon or a skewer.
Mix the cranberry sauce and vanilla pudding in a bowl until smooth.
Pour the cranberry-pudding mixture over the poked cake, ensuring it gets into all the holes.
Refrigerate the cake for at least 2 hours, or overnight for best results.
Spread whipped topping over the chilled cake.
Garnish with fresh cranberries before serving.