Combine the water, vinegar, maple syrup, salt, and peppercorns, stirring, until the salt dissolves. Place the pork tenderloins in a large food storage bag, add the brine, and 4 rosemary sprigs. Refrigerate for 2-4 hours. Remove from refrigerator, discard the brine, and dry off the tenderloins.
Preheat the oven to 400°F. Pour oil into a large oven-proof skillet and heat over medium-high heat. Add the tenderloins and sear on all sides, about 5 minutes. Put in the oven and roast for 10-15 minutes or until an instant-read thermometer reaches 140°F (the pork will come up to 145°F as it rests). Transfer the tenderloins to a cutting board and cover loosely with foil. Let rest for 10 minutes.
Place the skillet back on the stove over medium-high heat. Stir in the minced rosemary, cooking until fragrant. Add the wine and cook until reduced by half. Lower the heat to medium-low, add the cranberry sauce, and cook, stirring, until the cranberry sauce has loosened and is more liquified.