diff --git a/services/device/usb/mojo/device_impl.cc b/services/device/usb/mojo/device_impl.cc
index 7f34bfb1a5222..468f7014b6845 100644
--- a/services/device/usb/mojo/device_impl.cc
+++ b/services/device/usb/mojo/device_impl.cc
@@ -407,6 +407,26 @@ void DeviceImpl::SetInterfaceAlternateSetting(
     return;
   }
 
+  // SET_INTERFACE is a control transfer addressed to an interface. Apply the
+  // same protected-class policy that ClaimInterface() and
+  // HasControlTransferPermission() enforce so that a compromised renderer
+  // cannot use this entry point to drive USBDEVFS_SETINTERFACE against a
+  // blocked interface class.
+  const mojom::UsbConfigurationInfo* config = device_->GetActiveConfiguration();
+  if (config) {
+    auto interface_it =
+        std::ranges::find(config->interfaces, interface_number,
+                          &mojom::UsbInterfaceInfo::interface_number);
+    if (interface_it != config->interfaces.end()) {
+      for (const auto& alternate : (*interface_it)->alternates) {
+        if (blocked_interface_classes_.contains(alternate->class_code)) {
+          std::move(callback).Run(false);
+          return;
+        }
+      }
+    }
+  }
+
   device_handle_->SetInterfaceAlternateSetting(
       interface_number, alternate_setting, std::move(callback));
 }
diff --git a/services/device/usb/usb_device_handle_usbfs.cc b/services/device/usb/usb_device_handle_usbfs.cc
index 1ce133cec5d59..6565c778b583e 100644
--- a/services/device/usb/usb_device_handle_usbfs.cc
+++ b/services/device/usb/usb_device_handle_usbfs.cc
@@ -689,6 +689,16 @@ void UsbDeviceHandleUsbfs::SetInterfaceAlternateSetting(
     return;
   }
 
+  // Match the macOS and Windows backends: do not forward SET_INTERFACE for an
+  // interface that has not been claimed. Without this, the kernel auto-claims
+  // the interface for our fd (drivers/usb/core/devio.c::checkintf()).
+  if (!IsInterfaceClaimedByThis(interface_number)) {
+    USB_LOG(DEBUG) << "Interface " << interface_number << " was not claimed.";
+    task_runner_->PostTask(FROM_HERE,
+                           base::BindOnce(std::move(callback), false));
+    return;
+  }
+
   // USBDEVFS_SETINTERFACE is synchronous because it issues a SET_INTERFACE
   // request to the device so it must be performed on a thread where it is okay
   // to block.