The 6 most common attack vectors in Laravel

Understanding how attackers get in is the first step to keeping them out.

This chapter covers the six most common attack vectors we’ve identified targeting Laravel applications. Each one has been used in real-world attacks - including critical CVEs discovered in 2024-2026.

Vector 1: Debug mode exploitation

The most embarrassing vulnerability is often the most common: leaving APP_DEBUG=true in production.

Why it’s dangerous

When APP_DEBUG=true:

• Full stack traces reveal file paths, database credentials, and environment variables
• Error pages expose your application’s internal structure
• XSS vulnerabilities in the error page allow script injection
• Session data may be visible in debug output

The attack

1. Attacker triggers an error (malformed input, missing route)
2. Debug page reveals sensitive information
3. With XSS, attacker can steal admin session cookies
4. Full application compromise follows

Detection

Check your production environment:

// .env (WRONG - in production)
APP_ENV=production
APP_DEBUG=true  // NEVER do this!

// This combination is actively dangerous
// CVE-2024-13919 makes this exploitable

Fix

# In production .env
APP_DEBUG=false
APP_ENV=production

Vector 2: Livewire hydration smuggling

This is the most critical Laravel ecosystem vulnerability discovered in recent years.

How it works

Livewire components serialize their state to JSON for client-server communication. The vulnerability exists in how this data is deserialized (hydrated):

1. Attacker crafts malicious JSON payload
2. Payload contains serialized PHP objects
3. During hydration, these objects are unserialized
4. Gadget chains execute arbitrary code

Attack indicators

Watch for these in your logs:

• Unusual Livewire component requests
• Malformed JSON in wire:snapshot
• Unexpected object types in hydration errors
• __PHP_Incomplete_Class in error messages

Fix

composer require livewire/livewire:^3.6.4

Vector 3: Environment variable injection

A subtle but devastating attack that exploits PHP’s register_argc_argv setting.

The Attack

When register_argc_argv is enabled (default on many systems):

https://yoursite.com/?APP_ENV=local&APP_DEBUG=true

This query string can override your environment variables, enabling debug mode or changing the application environment.

Affected versions

Detection

// Check PHP configuration
if (ini_get('register_argc_argv') === '1') {
  echo "VULNERABLE: register_argc_argv is enabled";
}

Fix

Two options:

1. Update Laravel to patched versions
2. Disable in php.ini:

register_argc_argv = Off

Vector 4: Laravel pulse RCE

If you use Laravel Pulse for monitoring, this one’s for you.

The attack

1. Attacker accesses Pulse dashboard (often unprotected)
2. Exploits public remember() method
3. Injects malicious cached data
4. Cached data executes on subsequent requests

Fix

composer require laravel/pulse:^1.3.1

Also ensure Pulse access is restricted:

// In PulseServiceProvider or Gate
Gate::define('viewPulse', function ($user) {
  return $user->isAdmin();
});

Vector 5: File upload exploitation

The attack vector we experienced firsthand. Twice.

Why Laravel apps are vulnerable

Laravel makes file uploads easy - sometimes too easy:

// DANGEROUS: No extension validation
public function upload(Request $request)
{
  $request->validate([
      'file' => 'required|file|max:2048|mimes:jpg,png'
  ]);

  // mimes only checks MIME type, not extension!
  $path = $request->file('file')->store('public/uploads');

}

The mimes rule checks the file’s MIME type, which can be forged. An attacker can upload shell.php with a forged image/jpeg MIME type.

The safe way

public function upload(Request $request)
{
  $request->validate([
      'file' => [
          'required',
          'file',
          'max:2048',
          // Check actual extension
          function ($attribute, $value, $fail) {
              $ext = strtolower($value->getClientOriginalExtension());
              $allowed = ['jpg', 'jpeg', 'png', 'gif', 'pdf'];
              if (!in_array($ext, $allowed)) {
                  $fail('Invalid file type.');
              }
              // Also block PHP
              if (in_array($ext, ['php', 'phtml', 'php3', 'php4', 'php5', 'phar'])) {
                  $fail('PHP files are not allowed.');
              }
          },
      ],
  ]);

  // Generate safe filename
  $safeName = Str::uuid() . '.' . $request->file('file')
      ->getClientOriginalExtension();

  $path = $request->file('file')->storeAs('uploads', $safeName);

}

Critical: Block PHP in upload directories

Add .htaccess to prevent PHP execution:

# storage/app/public/.htaccess
<FilesMatch "\.php$">
    Deny from all
</FilesMatch>

# Or completely disable PHP
php_flag engine off

Vector 6: APP_KEY Deserialization

If your APP_KEY leaks, it’s game over.

Why APP_KEY matters

Laravel uses APP_KEY to:

• Encrypt cookies and session data
• Sign data with encrypt() and decrypt()
• Generate secure tokens

The attack chain

1. Attacker obtains APP_KEY (from exposed .env, git history, error pages)
2. Crafts malicious serialized PHP object
3. Encrypts it with the stolen key
4. Sends encrypted payload as cookie or input
5. Laravel decrypts and unserializes it
6. Gadget chain executes arbitrary code

Attack pattern detection

// Attacker uses decrypt() with user input
$payload = decrypt($_POST['data']);  // DANGEROUS!

// Or unserializes decrypted data
$data = unserialize(decrypt($input)); // CRITICAL!

Prevention

1. Never commit .env to git

   # .gitignore
   .env
   .env.backup
   .env.production

2. Check git history for leaks

   git log -p --all -S 'APP_KEY'

3. Rotate keys if compromised

   php artisan key:generate
   # Then invalidate all sessions

4. Never pass encrypted user input to unserialize()

Summary: The 6 Vectors

Next: Chapter 4 - The 87 Signatures: A Deep Dive into PHP Malware →

In the next chapter, we’ll examine the specific malware patterns attackers use - the 87 signatures our research identified targeting PHP and Laravel applications.