# Symfony PATH_INFO Authorization Bypass: GHSA-3rg7-wf37-54rm

> Symfony HTTP Foundation vulnerability allows authorization bypass through incorrect PATH_INFO parsing.

**URL:** https://www.ciptadusa.com/blog/symfony-path-info-authorization-bypass  
**Type:** blog  
**Author:** PT Cipta Dua Saudara  
**Category:** Application Security  
**Published:** 2026-05-30  
**Cover:** https://www.ciptadusa.com/media/defaults/blog-cover.svg  

## Article

# Symfony PATH_INFO Authorization Bypass: GHSA-3rg7-wf37-54rm

## Overview

A security vulnerability was discovered in Symfony's HTTP Foundation component that allows limited authorization bypass through incorrect PATH_INFO parsing. Tracked as GHSA-3rg7-wf37-54rm, this vulnerability affects multiple Symfony versions and can lead to security control circumvention.

## Technical Details

### Vulnerability Description

The vulnerability exists in how Symfony's HttpFoundation component parses the `PATH_INFO` server variable. Incorrect parsing can lead to discrepancies between the path used for authorization decisions and the actual path being accessed.

### Root Cause

Symfony's request handling processes `PATH_INFO` for routing and authorization. When the path is parsed differently by various components of the application, attackers can exploit these inconsistencies to bypass access controls.

### Affected Versions

- Symfony 5.x (fixed in 5.4.50)
- Symfony 6.x (fixed in 6.4.29)
- Symfony 7.x (fixed in 7.3.7)

### Attack Mechanism

```php
// Simplified attack scenario
// Authorization middleware sees:
// PATH_INFO = "/admin/dashboard"
// Grants access based on this path

// But the actual request reaches:
// PATH_INFO = "/admin/dashboard/../../../public/resource"
// Accessing restricted resource through path traversal
```

## Exploitation

### Attack Scenario

1. **Craft Request**: Attacker creates request with specially formatted PATH_INFO
2. **Authorization Check**: Middleware evaluates the original path
3. **Routing Resolution**: Application resolves to different path
4. **Access Granted**: Attacker accesses restricted resource

### Example Attack

```http
GET /admin/dashboard HTTP/1.1
Host: vulnerable-app.com
# Path is normalized differently at authorization vs. routing
```

## Impact Assessment

### Severity: Medium

- **Confidentiality**: Medium - Access to restricted resources
- **Integrity**: Low - Limited modification potential
- **Availability**: None

### Business Impact

- Unauthorized access to admin panels
- Data exposure
- Compliance violations

## Mitigation Strategies

### Immediate Actions

1. **Update Symfony** to patched versions:
   - Symfony 5.4.50 or later
   - Symfony 6.4.29 or later
   - Symfony 7.3.7 or later

2. **Review Authorization Logic**:
   ```php
   // Check current implementation
   // Ensure authorization happens at the correct layer
   ```

### Defense in Depth

```php
// Secure authorization implementation
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Security\Core\Authorization\AuthorizationCheckerInterface;

class SecureAuthorizationMiddleware
{
    private $authorizationChecker;
    
    public function __construct(AuthorizationCheckerInterface $authorizationChecker)
    {
        $this->authorizationChecker = $authorizationChecker;
    }
    
    public function handle(Request $request, callable $next)
    {
        // Get the resolved path, not the raw PATH_INFO
        $path = $request->getPathInfo();
        
        // Normalize the path
        $path = $this->normalizePath($path);
        
        // Perform authorization check
        if (!$this->isPathAllowed($path)) {
            throw new AccessDeniedException('Access denied');
        }
        
        return $next($request);
    }
    
    private function normalizePath(string $path): string
    {
        // Remove path traversal attempts
        $path = str_replace(['../', '..\\'], '', $path);
        // Normalize slashes
        $path = preg_replace('#/+#', '/', $path);
        // Remove trailing slash
        $path = rtrim($path, '/');
        
        return $path;
    }
    
    private function isPathAllowed(string $path): bool
    {
        // Implement your authorization logic
        return $this->authorizationChecker->isGranted('ACCESS', $path);
    }
}
```

### Routing Configuration

```php
// config/routes.yaml
controllers:
    resource: ../src/Controller/
    type: attribute
    # Ensure consistent path handling
    trailing_slash_on_root: false
```

## Related Symfony Security Issues

### Other HTTP Foundation Vulnerabilities

Symfony has addressed several related security issues:

1. **Request Smuggling**: Inconsistent request parsing
2. **Header Injection**: Improper header value handling
3. **Session Fixation**: Session ID regeneration issues

### Security Best Practices

```php
// Symfony security configuration
// config/packages/security.yaml
security:
    access_control:
        # Use explicit paths, not patterns
        - { path: ^/admin, roles: ROLE_ADMIN }
        - { path: ^/api/private, roles: ROLE_API }
        
    # Enable security firewalls
    firewalls:
        main:
            # Configure authentication
            pattern: ^/
            form_login: true
            logout: true
```

## Symfony Security Features

### Built-in Protections

```php
// Use Symfony's security component
use Symfony\Component\Security\Core\Security;

class SecureController extends AbstractController
{
    #[IsGranted('ROLE_ADMIN')]
    public function adminDashboard(): Response
    {
        // Only accessible to admins
        return $this->render('admin/dashboard.html.twig');
    }
    
    #[IsGranted('POST_EDIT', subject: 'post')]
    public function editPost(Post $post): Response
    {
        // Only accessible if user can edit this specific post
        return $this->render('post/edit.html.twig', ['post' => $post]);
    }
}
```

### Path-based Access Control

```php
// Custom voter for path-based authorization
use Symfony\Component\Security\Core\Authorization\Voter\Voter;
use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;

class PathVoter extends Voter
{
    protected function supports(string $attribute, mixed $subject): bool
    {
        return $attribute === 'PATH_ACCESS';
    }
    
    protected function voteOnAttribute(string $attribute, mixed $subject, TokenInterface $token): bool
    {
        $path = $subject;
        $user = $token->getUser();
        
        // Implement path-based authorization logic
        return $this->isPathAllowedForUser($path, $user);
    }
    
    private function isPathAllowedForUser(string $path, UserInterface $user): bool
    {
        // Define allowed paths for each role
        $allowedPaths = [
            'ROLE_ADMIN' => ['/admin'],
            'ROLE_USER' => ['/dashboard', '/profile'],
        ];
        
        foreach ($user->getRoles() as $role) {
            if (isset($allowedPaths[$role])) {
                foreach ($allowedPaths[$role] as $allowedPath) {
                    if (str_starts_with($path, $allowedPath)) {
                        return true;
                    }
                }
            }
        }
        
        return false;
    }
}
```

## Monitoring and Detection

### Logging Authorization Events

```php
// Monitor authorization attempts
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Security\Core\Event\AuthorizationEvent;

class AuthorizationLogger implements EventSubscriberInterface
{
    public static function getSubscribedEvents(): array
    {
        return [
            AuthorizationEvent::class => 'onAuthorization',
        ];
    }
    
    public function onAuthorization(AuthorizationEvent $event): void
    {
        $request = $event->getRequest();
        $path = $request->getPathInfo();
        $user = $event->getToken()->getUser();
        
        // Log authorization decisions
        $this->logger->info('Authorization check', [
            'path' => $path,
            'user' => $user->getUserIdentifier(),
            'granted' => $event->isGranted(),
        ]);
    }
}
```

## Best Practices for Symfony Security

### Path Handling

1. **Normalize paths early**: Remove traversal attempts
2. **Use Symfony's router**: Don't parse paths manually
3. **Validate input**: Sanitize all user-supplied path components

### Authorization Layer

1. **Use voters**: Implement fine-grained authorization
2. **Apply at controller level**: Use annotations/attributes
3. **Test thoroughly**: Include path manipulation in test cases

## Conclusion

GHSA-3rg7-wf37-54rm highlights the importance of consistent path handling in web applications. By updating Symfony and implementing proper path normalization, developers can prevent authorization bypass vulnerabilities.

## References

- [Symfony Security Advisory GHSA-3rg7-wf37-54rm](https://github.com/symfony/symfony/security/advisories/GHSA-3rg7-wf37-54rm)
- [Symfony Security Documentation](https://symfony.com/doc/current/security.html)
- [Symfony HttpFoundation Component](https://symfony.com/doc/current/components/http_foundation.html)

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