diff --git a/.changes/built-team-invitation-links-from-the.md b/.changes/built-team-invitation-links-from-the.md
new file mode 100644
index 0000000000..b31495cf38
--- /dev/null
+++ b/.changes/built-team-invitation-links-from-the.md
@@ -0,0 +1,4 @@
+---
+type: security
+---
+Built team invitation links from the instance URL instead of the request host, when no instance domain is set
diff --git a/app/Livewire/Team/InviteLink.php b/app/Livewire/Team/InviteLink.php
index 6d950245a9..c3cb9844e1 100644
--- a/app/Livewire/Team/InviteLink.php
+++ b/app/Livewire/Team/InviteLink.php
@@ -66,14 +66,12 @@ class InviteLink extends Component
         $this->generateInviteLink(sendEmail: false);
     }
 
+    /**
+     * Build the link from the instance URL, not from the request host, which a client can set.
+     */
     private function invitationUrl(string $routeName, array $parameters): string
     {
-        $fqdn = instanceSettings()->fqdn;
-        if (filled($fqdn)) {
-            return rtrim($fqdn, '/').route($routeName, $parameters, false);
-        }
-
-        return route($routeName, $parameters);
+        return rtrim(base_url(), '/').route($routeName, $parameters, false);
     }
 
     private function generateInviteLink(bool $sendEmail = false)
diff --git a/tests/Feature/Team/TeamInvitationPrivilegeEscalationTest.php b/tests/Feature/Team/TeamInvitationPrivilegeEscalationTest.php
index 06013935ff..406ed528f9 100644
--- a/tests/Feature/Team/TeamInvitationPrivilegeEscalationTest.php
+++ b/tests/Feature/Team/TeamInvitationPrivilegeEscalationTest.php
@@ -6,6 +6,7 @@ use App\Models\Team;
 use App\Models\TeamInvitation;
 use App\Models\User;
 use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Facades\URL;
 use Livewire\Livewire;
 
 uses(RefreshDatabase::class);
@@ -185,15 +186,19 @@ describe('privilege escalation prevention', function () {
         expect($invitation->link)->toStartWith('https://coolify.example.com/auth/link?token=');
     });
 
-    test('new user invitation magic link falls back to route url when instance fqdn is not configured', function () {
+    test('new user invitation magic link ignores a spoofed request host when instance fqdn is not configured', function () {
         InstanceSettings::unguarded(fn () => InstanceSettings::query()->updateOrCreate(
             ['id' => 0],
-            ['fqdn' => null]
+            ['fqdn' => null, 'public_ipv4' => null, 'public_ipv6' => null]
         ));
+        config(['app.url' => 'http://coolify.internal:8000']);
 
         $this->actingAs($this->owner);
         session(['currentTeam' => $this->team]);
 
+        // A forwarded Host header from the client sets the request root URL.
+        URL::forceRootUrl('http://evil.example');
+
         Livewire::test(InviteLink::class)
             ->set('email', 'fallback-invitee@example.com')
             ->set('role', 'member')
@@ -202,8 +207,8 @@ describe('privilege escalation prevention', function () {
 
         $invitation = TeamInvitation::whereEmail('fallback-invitee@example.com')->firstOrFail();
 
-        $expectedPrefix = route('auth.link', ['token' => '']);
-        expect($invitation->link)->toStartWith($expectedPrefix);
+        expect($invitation->link)->toStartWith('http://coolify.internal:8000/auth/link?token=')
+            ->not->toContain('evil.example');
     });
 
     test('member cannot bypass policy by calling viaEmail', function () {