Every one of them has vulnerabilities that a knowledgeable thief could theoretically exploit.
2016年12月四级真题(第一套)阅读 Section B
柯林斯高阶英汉双解学习词典释义
ADV
从理论上说;照理说
You use theoretically to say that although something is supposed to be true or to happen in the way stated, it may not in fact be true or happen in that way.