The wonderful designers of my kitchen installed a tall (oak) pantry cabinet next to the range. I am concerned that this is a fire hazard. Is there anything I can do to mitigate the heat from the stove top?
Virtually all appliances have published minimum clearance requirements. You should be able to look up your model online and find the installation instructions, including said requirements.
E.g. this randomly picked Kitchenaid gas range requires 24"-30" clearance above the stove and 5" from the side of the stove to a wall, among other requirements.
If your setup meets the manufacturer's recommendations, you are almost certainly OK and I wouldn't worry about it. If not, you could try some of @HerrBag's suggestions or ideally remedy the situation properly by fixing the layout.