Welcome Newcomer. There could be several reasons for the high temps, and by the way, those temps are very dangerous.
First thing you should do is clean out the dust (if any) built up on your fans and heatsink.
Second thing you should do is make sure all of your fans are working.
Next, if the problem hasn't been fixed yet, remove your heatsink and reapply thermal paste to the bottom of the the heatsink. Carefully reinstall the heatsink while applying even pressure.
Lastly, if you need to, get an aftermarket heatsink.