---
title: "Create a Mass Assignment Lab With Me"
url: https://daily.dev/posts/create-a-mass-assignment-lab-with-me-efshkfw1a
source_url: https://infosecwriteups.com/create-a-mass-assignment-lab-with-me-30bcc5d30b0f
type: article
source: "InfoSec Write-ups"
published: 2026-05-18T11:20:36.999Z
updated: 2026-05-18T11:21:03.034Z
tags: ["nodejs", "appsec", "express", "web-security"]
reading_time: 11
upvotes: 0
comments: 0
language: en
---

> ## Documentation Index
> Fetch the complete documentation index at: https://daily.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Create a Mass Assignment Lab With Me

**[InfoSec Write-ups](https://daily.dev/sources/infosecwriteups)** · 11 min read · 0 upvotes · 0 comments

## Summary

A hands-on tutorial for building a deliberately vulnerable Node.js/Express lab that demonstrates the mass assignment vulnerability. Starting from GitHub repo setup, it walks through creating a simple web app with user registration, then intentionally introduces the flaw by spreading req.body into a user object — allowing an attacker to override the role field and gain admin access. The post explains why the spread operator causes the vulnerability, why database defaults don't protect against it, and how to fix it by explicitly destructuring only expected fields.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://infosecwriteups.com/create-a-mass-assignment-lab-with-me-30bcc5d30b0f>

## Similar posts on daily.dev

- [How to Fix Common Web Application Security Vulnerabilities in Node.js](https://daily.dev/posts/how-to-fix-common-web-application-security-vulnerabilities-in-node-js-nhhyrhesv) · freeCodeCamp · 3 upvotes · 0 comments
- [Making A SQLi Lab Is Not Difficult, Build One With Me.](https://daily.dev/posts/making-a-sqli-lab-is-not-difficult-build-one-with-me--zjnbh9hrp) · InfoSec Write-ups · 0 upvotes · 0 comments

---

Tags: [#nodejs](https://daily.dev/tags/nodejs), [#appsec](https://daily.dev/tags/appsec), [#express](https://daily.dev/tags/express), [#web-security](https://daily.dev/tags/web-security)

[View this post on daily.dev](https://daily.dev/posts/create-a-mass-assignment-lab-with-me-efshkfw1a)