Combine cranberries, white sugar, and water in a saucepan over medium heat. Cook, stirring occasionally, until the cranberries have popped and the mixture has thickened, about 15 minutes. Remove from the heat and let cool.

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.

Stir together cake mix, melted butter, eggs, oats, brown sugar, ginger, and cinnamon in a large bowl until combined. Reserve 1 1/2 cups of the mixture. Press the remaining mixture evenly into the bottom of the prepared baking dish. Spread the cooled cranberry mixture over the crust. Crumble the reserved mixture evenly over the top.

Bake in the preheated oven until the top is lightly browned, 35 to 40 minutes. Cool in the pan for about 40 minutes before slicing into 24 bars.