@@ -19,6 +19,7 @@ class Kernel extends HttpKernel
         \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
         Middleware\TrimStrings::class,
         \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
+        Middleware\TrustHosts::class,
         Middleware\TrustProxies::class,
         Middleware\BrowserCache::class,
         ServerTimingMiddleware::class,
@@ -88,7 +89,7 @@ class Kernel extends HttpKernel
         'no-cache' => Middleware\NoCache::class,
         'admin' => Middleware\IsAdmin::class,
         'etag' => Middleware\Etag\HandleEtag::class,
-        'file_size_check' => Middleware\FileSizeCheck::class,
+        'file_size_check' => Middleware\FileSizeCheck::class
     ];
 
     /**
 
@@ -0,0 +1,39 @@
+<?php
+
+namespace ProcessMaker\Http\Middleware;
+
+use Illuminate\Http\Middleware\TrustHosts as Middleware;
+use Closure;
+use Illuminate\Http\Request;
+
+class TrustHosts extends Middleware
+{
+    public function hosts(): array
+    {
+        $trustedHost = $this->allSubdomainsOfApplicationUrl();
+        return [$trustedHost];
+    }
+
+    public function handle(Request $request, $next)
+    {
+        if ($request->hasHeader('X-Forwarded-Host')) {
+            $forwardedHost = $request->header('X-Forwarded-Host');
+            $trustedPattern = $this->allSubdomainsOfApplicationUrl();
+            
+            if (!$this->hostIsValid($forwardedHost, $trustedPattern)) {
+                \Log::warning('Rejected request with untrusted X-Forwarded-Host', [
+                    'forwarded_host' => $forwardedHost,
+                    'trusted_pattern' => $trustedPattern
+                ]);
+                abort(400, 'Invalid Host Header');
+            }
+        }
+
+        return parent::handle($request, $next);
+    }
+
+    protected function hostIsValid(string $host, string $pattern): bool
+    {
+        return preg_match('/' . str_replace('/', '\/', $pattern) . '/', $host) === 1;
+    }
+} 
@@ -0,0 +1,61 @@
+<?php
+
+namespace Tests\Feature\Http\Middleware;
+
+use Tests\TestCase;
+use ProcessMaker\Http\Middleware\TrustHosts;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Config;
+
+class TrustHostsTest extends TestCase
+{
+    protected $middleware;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->middleware = new TrustHosts($this->app);
+    }
+
+    public function test_valid_trusted_host()
+    {
+        // Set app URL for testing
+        Config::set('app.url', 'https://example.processmaker.net');
+
+        $request = Request::create('https://subdomain.example.processmaker.net');
+        $request->headers->set('X-Forwarded-Host', 'subdomain.example.processmaker.net');
+
+        $response = $this->middleware->handle($request, function ($req) {
+            return response()->json(['status' => 'success']);
+        });
+
+        $this->assertEquals(200, $response->status());
+    }
+
+    public function test_invalid_trusted_host()
+    {
+        // Set app URL for testing
+        Config::set('app.url', 'https://example.processmaker.net');
+
+        $request = Request::create('https://malicious-site.com');
+        $request->headers->set('X-Forwarded-Host', 'malicious-site.com');
+
+        $this->expectException(\Symfony\Component\HttpKernel\Exception\HttpException::class);
+        $this->expectExceptionMessage('Invalid Host Header');
+
+        $this->middleware->handle($request, function ($req) {
+            return response()->json(['status' => 'success']);
+        });
+    }
+
+    public function test_missing_forwarded_host()
+    {
+        $request = Request::create('https://example.processmaker.net');
+        
+        $response = $this->middleware->handle($request, function ($req) {
+            return response()->json(['status' => 'success']);
+        });
+
+        $this->assertEquals(200, $response->status());
+    }
+}