diff --git a/controllers/metal3.io/baremetalhost_controller_test.go b/controllers/metal3.io/baremetalhost_controller_test.go
index 52c3515179..4dc0655d09 100644
--- a/controllers/metal3.io/baremetalhost_controller_test.go
+++ b/controllers/metal3.io/baremetalhost_controller_test.go
@@ -41,6 +41,10 @@ const (
 )
 
 func newSecret(name string, data map[string]string) *corev1.Secret {
+	return newSecretInNamespace(name, namespace, data)
+}
+
+func newSecretInNamespace(name, namespace string, data map[string]string) *corev1.Secret {
 	secretData := make(map[string][]byte)
 	for k, v := range data {
 		secretData[k] = []byte(base64.StdEncoding.EncodeToString([]byte(v)))
diff --git a/controllers/metal3.io/host_config_data.go b/controllers/metal3.io/host_config_data.go
index 0a298e24d9..037a0372c4 100644
--- a/controllers/metal3.io/host_config_data.go
+++ b/controllers/metal3.io/host_config_data.go
@@ -2,11 +2,11 @@ package controllers
 
 import (
 	"github.com/go-logr/logr"
-	corev1 "k8s.io/api/core/v1"
-	"k8s.io/apimachinery/pkg/types"
-
 	metal3api "github.com/metal3-io/baremetal-operator/apis/metal3.io/v1alpha1"
 	"github.com/metal3-io/baremetal-operator/pkg/secretutils"
+	"github.com/pkg/errors"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/types"
 )
 
 // hostConfigData is an implementation of host configuration data interface.
@@ -21,6 +21,10 @@ type hostConfigData struct {
 // parameter to detirmine which data to return in case secret contins multiple
 // keys.
 func (hcd *hostConfigData) getSecretData(name, namespace, dataKey string) (string, error) {
+	if namespace != hcd.host.Namespace {
+		return "", errors.Errorf("%s secret must be in same namespace as host %s/%s", dataKey, hcd.host.Namespace, hcd.host.Name)
+	}
+
 	key := types.NamespacedName{
 		Name:      name,
 		Namespace: namespace,
diff --git a/controllers/metal3.io/host_config_data_test.go b/controllers/metal3.io/host_config_data_test.go
index f763a6e8a7..4ecc5a6d68 100644
--- a/controllers/metal3.io/host_config_data_test.go
+++ b/controllers/metal3.io/host_config_data_test.go
@@ -324,6 +324,54 @@ func TestProvisionWithHostConfig(t *testing.T) {
 			ExpectedNetworkData: "",
 			ErrNetworkData:      true,
 		},
+		{
+			Scenario: "user-data secret in different namespace",
+			Host: newHost("host-user-data",
+				&metal3api.BareMetalHostSpec{
+					BMC: metal3api.BMCDetails{
+						Address:         "ipmi://192.168.122.1:6233",
+						CredentialsName: defaultSecretName,
+					},
+					UserData: &corev1.SecretReference{
+						Name:      "user-data",
+						Namespace: "other-namespace",
+					},
+				}),
+			UserDataSecret: newSecretInNamespace("user-data", "other-namespace", map[string]string{"userData": "somedata"}),
+			ErrUserData:    true,
+		},
+		{
+			Scenario: "meta-data secret in different namespace",
+			Host: newHost("host-user-data",
+				&metal3api.BareMetalHostSpec{
+					BMC: metal3api.BMCDetails{
+						Address:         "ipmi://192.168.122.1:6233",
+						CredentialsName: defaultSecretName,
+					},
+					MetaData: &corev1.SecretReference{
+						Name:      "meta-data",
+						Namespace: "other-namespace",
+					},
+				}),
+			NetworkDataSecret: newSecretInNamespace("meta-data", "other-namespace", map[string]string{"metaData": "key: value"}),
+			ErrMetaData:       true,
+		},
+		{
+			Scenario: "network-data secret in different namespace",
+			Host: newHost("host-user-data",
+				&metal3api.BareMetalHostSpec{
+					BMC: metal3api.BMCDetails{
+						Address:         "ipmi://192.168.122.1:6233",
+						CredentialsName: defaultSecretName,
+					},
+					NetworkData: &corev1.SecretReference{
+						Name:      "net-data",
+						Namespace: "other-namespace",
+					},
+				}),
+			NetworkDataSecret: newSecretInNamespace("net-data", "other-namespace", map[string]string{"networkData": "key: value"}),
+			ErrNetworkData:    true,
+		},
 	}
 
 	for _, tc := range testCases {
@@ -379,7 +427,7 @@ func TestProvisionWithHostConfig(t *testing.T) {
 			}
 
 			if actualMetaData != tc.ExpectedMetaData {
-				t.Fatal(fmt.Errorf("Failed to assert MetaData. Expected '%s' got '%s'", actualMetaData, tc.ExpectedMetaData))
+				t.Fatal(fmt.Errorf("Failed to assert MetaData. Expected '%s' got '%s'", tc.ExpectedMetaData, actualMetaData))
 			}
 		})
 	}