diff --git a/core/serializers.py b/core/serializers.py
index 41a20e7..12f6ed9 100644
--- a/core/serializers.py
+++ b/core/serializers.py
@@ -8,6 +8,7 @@ from core.models import Image, Board
 from core.models import Pin
 from django_images.models import Thumbnail
 from users.serializers import UserSerializer
+from users.models import User
 
 
 def filter_private_pin(request, query):
@@ -219,8 +220,14 @@ class BoardSerializer(serializers.HyperlinkedModelSerializer):
         return PinSerializer(pin, context=self.context).data
 
     @staticmethod
-    def _get_list(pins_id):
-        return tuple(Pin.objects.filter(id__in=pins_id))
+    def _get_list(pins_id, submitter: User):
+        pins = Pin.objects.filter(id__in=pins_id)
+        valid_pins = []
+        for pin in pins:
+            if pin.private and pin.submitter != submitter:
+                continue
+            valid_pins.append(pin)
+        return valid_pins
 
     def update(self, instance: Board, validated_data):
         pins_to_add = validated_data.pop("pins_to_add", [])
@@ -237,11 +244,11 @@ class BoardSerializer(serializers.HyperlinkedModelSerializer):
         changed = False
         if pins_to_add:
             changed = True
-            for pin in self._get_list(pins_to_add):
+            for pin in self._get_list(pins_to_add, instance.submitter):
                 instance.pins.add(pin)
         if pins_to_remove:
             changed = True
-            for pin in self._get_list(pins_to_remove):
+            for pin in self._get_list(pins_to_remove, instance.submitter):
                 instance.pins.remove(pin)
         if changed:
             instance.save()
diff --git a/core/tests/api.py b/core/tests/api.py
index 20144b6..ac1c960 100644
--- a/core/tests/api.py
+++ b/core/tests/api.py
@@ -53,6 +53,13 @@ class BoardPrivacyTests(APITestCase):
     def tearDown(self):
         _teardown_models()
 
+    def _create_pin_with_non_owner(self, private):
+        image = create_image()
+        pin = create_pin(self.non_owner, image=image, tags=[])
+        pin.private = private
+        pin.save()
+        return pin
+
     def test_should_non_owner_and_anonymous_user_has_no_permission_to_list_private_board(self):
         resp = self.client.get(self.boards_url)
         self.assertEqual(len(resp.json()), 0, resp.json())
@@ -79,6 +86,30 @@ class BoardPrivacyTests(APITestCase):
         resp = self.client.get(self.board_url)
         self.assertEqual(resp.status_code, 200)
 
+    def test_should_owner_has_no_permission_to_add_private_pin_of_other_user_to_board(self):
+        self.client.login(username=self.owner.username, password='password')
+
+        private_pin_of_other_user = self._create_pin_with_non_owner(True)
+
+        resp = self.client.patch(self.board_url, data={"pins_to_add": [private_pin_of_other_user.id, ]})
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get(self.board_url)
+        self.assertEqual(resp.status_code, 200)
+        self.assertEqual(resp.json()['total_pins'], 0, resp.json())
+
+    def test_should_owner_has_permission_to_add_non_private_pin_of_other_user_to_board(self):
+        self.client.login(username=self.owner.username, password='password')
+
+        private_pin_of_other_user = self._create_pin_with_non_owner(False)
+
+        resp = self.client.patch(self.board_url, data={"pins_to_add": [private_pin_of_other_user.id, ]})
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get(self.board_url)
+        self.assertEqual(resp.status_code, 200)
+        self.assertEqual(resp.json()['total_pins'], 1, resp.json())
+
 
 class PinPrivacyTests(APITestCase):