How can I repair cracked open rubber snow/hiking boots? Something better...

...than super-glue? I have a pair of Columbia winter boots (leather upper, rubber foot), and noticed when I went to put them on this year, that the rubber has cracked open down to the sole, and come apart from the leather upper. How this happened, I have no clue, but I cannot afford a new pair! So the rubber is over the insulated inside part, and touching leather. I need to reconnect the three materials, and seam together the cracked rubber in a waterproof way. Can anyone suggest a bonding agent, or repair method to bring these boots back to life? Thank you!