Preheat oven to 400 degrees. Line a baking sheet with parchment or waxed paper. In a large bowl, stir together flour, sugar, baking powder, baking soda, salt, and orange zest.
With a pastry blender or two knives, cut butter into flour mixture until it resembles coarse meal. Stir in dried cranberries.
Make a well in the center of the mixture. Add buttermilk, and stir until just combined; do not overmix. Use a little more buttermilk if dough is too dry to work with.
Transfer dough to a lightly floured surface; shape into an 8-inch round. Transfer to baking sheet. Cut circle into 8 wedges; space them 1/2 inch apart (to prevent sticking, dust knife with flour). Bake until golden, 18 to 20 minutes.