Validation Bypass Affecting kind-of package, versions >=6.0.0 <6.0.3

  • Exploit Maturity

    Proof of concept

  • Attack Complexity


Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • snyk-id


  • published

    19 Jan 2020

  • disclosed

    16 Dec 2019

  • credit

    Feng Xiao

How to fix?

Upgrade kind-of to version 6.0.3 or higher.


kind-of is a package that gets the native type of a value.

Affected versions of this package are vulnerable to Validation Bypass. It leverages the built-in constructor of unsafe user-input to detect type information. However, a crafted payload can overwrite this built in attribute to manipulate the type detection result.

PoC by Feng Xiao

var kindOf = require('kind-of');

var user_input = {
  user: 'barney',
  age: 36,
  active: true,