diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal.go
index 12cc2f6f2c9..321bec385c5 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal.go
@@ -130,7 +130,7 @@ func (s JSON) MarshalJSON() ([]byte, error) {
 
 func (s *JSON) UnmarshalJSON(data []byte) error {
 	if len(data) > 0 && !bytes.Equal(data, nullLiteral) {
-		s.Raw = data
+		s.Raw = append(s.Raw[0:0], data...)
 	}
 	return nil
 }
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal_test.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal_test.go
index dae08bd5e3b..4ddab379c5d 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal_test.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1/marshal_test.go
@@ -148,3 +148,24 @@ func TestJSONSchemaPropsOrArrayMarshalJSON(t *testing.T) {
 		}
 	}
 }
+
+func TestJSONUnderlyingArrayReuse(t *testing.T) {
+	const want = `{"foo":"bar"}`
+
+	b := []byte(want)
+
+	var s JSON
+	if err := s.UnmarshalJSON(b); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// Underlying array is modified.
+	copy(b[2:5], "bar")
+	copy(b[8:11], "foo")
+
+	// If UnmarshalJSON copied the bytes of its argument, then it should not have been affected
+	// by the mutation.
+	if got := string(s.Raw); got != want {
+		t.Errorf("unexpected mutation, got %s want %s", got, want)
+	}
+}
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal.go
index 44941d82eff..43b90387872 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal.go
@@ -130,7 +130,7 @@ func (s JSON) MarshalJSON() ([]byte, error) {
 
 func (s *JSON) UnmarshalJSON(data []byte) error {
 	if len(data) > 0 && !bytes.Equal(data, nullLiteral) {
-		s.Raw = data
+		s.Raw = append(s.Raw[0:0], data...)
 	}
 	return nil
 }
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal_test.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal_test.go
index 99065ff95ad..c45e12f9993 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal_test.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/marshal_test.go
@@ -148,3 +148,24 @@ func TestJSONSchemaPropsOrArrayMarshalJSON(t *testing.T) {
 		}
 	}
 }
+
+func TestJSONUnderlyingArrayReuse(t *testing.T) {
+	const want = `{"foo":"bar"}`
+
+	b := []byte(want)
+
+	var s JSON
+	if err := s.UnmarshalJSON(b); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// Underlying array is modified.
+	copy(b[2:5], "bar")
+	copy(b[8:11], "foo")
+
+	// If UnmarshalJSON copied the bytes of its argument, then it should not have been affected
+	// by the mutation.
+	if got := string(s.Raw); got != want {
+		t.Errorf("unexpected mutation, got %s want %s", got, want)
+	}
+}