http://yq6bel7syh3wqexf5dklq5uqboiilvbw2aiu2l5ztrlghvzmoqmwffid.onion
Ironically, it allowed for the printing of an unlimited amount of coins. Along with performance upgrades, the Sapling protocol fixed that bug. One might wonder how we know that nobody took advantage of this vulnerability, printed an enormous amount of supply, and moved it to the shielded Sapling pool.