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NoSQL Injection in Symfony: How to Detect and Prevent

Modern web applications often use NoSQL databases such as MongoDB for flexibility and scalability. But with flexibility comes risk — improper query handling can lead to NoSQL injection vulnerabilities.

In this post, you’ll learn:
✅ What NoSQL injection is
✅ How it affects Symfony applications
✅ How to fix it with code examples
✅ How to scan your site for free

NoSQL Injection in Symfony: How to Detect and Prevent

You can also check out more cybersecurity best practices on our blog:
👉 Pentest Testing Corp


📖 What is NoSQL Injection?

NoSQL injection happens when unvalidated user input is directly passed into NoSQL queries. Unlike SQL injection, it exploits the flexible JSON-based queries used in databases like MongoDB.

For example, an attacker can craft input to manipulate the query logic and bypass authentication or extract sensitive data.


🛠️ NoSQL Injection Example in Symfony

Here’s an insecure snippet from a Symfony controller that fetches a user by username and password:

// src/Controller/LoginController.php
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;

class LoginController extends AbstractController
{
    public function login(Request $request)
    {
        $username = $request->get('username');
        $password = $request->get('password');

        $user = $this->getDoctrine()
                     ->getManager()
                     ->getRepository(User::class)
                     ->findOneBy([
                         'username' => $username,
                         'password' => $password
                     ]);

        if ($user) {
            return $this->json(['message' => 'Login successful']);
        }

        return $this->json(['error' => 'Invalid credentials'], 401);
    }
}
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🚨 The Problem:

If the backend uses MongoDB and the query is passed directly, an attacker can send input like:

username: { "$ne": null }
password: { "$ne": null }
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This bypasses the password check and logs in without valid credentials.


🧰 How to Fix NoSQL Injection in Symfony

✅ Use Parameterized Queries

In Symfony, when working with MongoDB (e.g., using Doctrine MongoDB ODM), always sanitize and cast inputs properly.

Example:

$cleanUsername = (string) $request->get('username');
$cleanPassword = (string) $request->get('password');

$user = $dm->getRepository(User::class)->findOneBy([
    'username' => $cleanUsername,
    'password' => $cleanPassword
]);
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Casting inputs to strings prevents attackers from injecting an array or object.

✅ Validate Input

Use Symfony validators to ensure input types and formats are correct.

use Symfony\Component\Validator\Constraints as Assert;

$constraints = new Assert\Collection([
    'username' => new Assert\Regex('/^[a-zA-Z0-9_]{3,20}$/'),
    'password' => new Assert\Length(['min' => 8])
]);
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🔍 How to Test for NoSQL Injection

The easiest way to check if your site is vulnerable is by using a security scanner.

🖼️ Screenshot: Free Website Vulnerability Scanner

Screenshot of the free tools webpage where you can access security assessment tools.

You can try our Website Vulnerability Scanner to scan your site for injection flaws, misconfigurations, and more. It generates a quick report you can act on.

🖼️ Screenshot: Vulnerability Assessment Report

An Example of a vulnerability assessment report generated with our free tool, providing insights into possible vulnerabilities.

A sample report showing detected issues to check Website Vulnerability and recommendations to fix them.


🔗 Related Services

If you need a more thorough assessment or remediation support, here are some of our premium services:

🌐 Web Application Penetration Testing

We perform manual and automated penetration testing of your Symfony and other web apps to uncover and fix vulnerabilities.

🤝 Offer Cybersecurity Services to Your Clients

If you’re an agency, partner with us and resell our pentesting services to your clients under your own brand.


📬 Stay Updated

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👨‍💻 Why You Should Care

With the rise of NoSQL databases in modern stacks, developers and security teams must stay ahead of injection risks. Symfony provides tools to help you write safe code, but it’s up to you to use them correctly.

Test your Symfony app today with our free tool:
👉 https://free.pentesttesting.com/


🚀 Learn More

For more cybersecurity articles and guides:
👉 Pentest Testing Corp Blog.

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