diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7fe3bf687..0c5e43123 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Security
 - OStatus: eliminate the possibility of a protocol downgrade attack.
 - OStatus: prevent following locked accounts, bypassing the approval process.
+- Mastodon API: respect post privacy in `/api/v1/statuses/:id/{favourited,reblogged}_by`
 
 ### Removed
 - **Breaking:** GNU Social API with Qvitter extensions support
diff --git a/lib/pleroma/web/mastodon_api/controllers/mastodon_api_controller.ex b/lib/pleroma/web/mastodon_api/controllers/mastodon_api_controller.ex
index c54462bb3..93ca44d31 100644
--- a/lib/pleroma/web/mastodon_api/controllers/mastodon_api_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/mastodon_api_controller.ex
@@ -842,6 +842,7 @@ def get_mascot(%{assigns: %{user: user}} = conn, _params) do
 
   def favourited_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
     with %Activity{} = activity <- Activity.get_by_id_with_object(id),
+         {:visible, true} <- {:visible, Visibility.visible_for_user?(activity, user)},
          %Object{data: %{"likes" => likes}} <- Object.normalize(activity) do
       q = from(u in User, where: u.ap_id in ^likes)
 
@@ -853,12 +854,14 @@ def favourited_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
       |> put_view(AccountView)
       |> render("accounts.json", %{for: user, users: users, as: :user})
     else
+      {:visible, false} -> {:error, :not_found}
       _ -> json(conn, [])
     end
   end
 
   def reblogged_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
     with %Activity{} = activity <- Activity.get_by_id_with_object(id),
+         {:visible, true} <- {:visible, Visibility.visible_for_user?(activity, user)},
          %Object{data: %{"announcements" => announces}} <- Object.normalize(activity) do
       q = from(u in User, where: u.ap_id in ^announces)
 
@@ -870,6 +873,7 @@ def reblogged_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
       |> put_view(AccountView)
       |> render("accounts.json", %{for: user, users: users, as: :user})
     else
+      {:visible, false} -> {:error, :not_found}
       _ -> json(conn, [])
     end
   end
diff --git a/test/web/mastodon_api/mastodon_api_controller_test.exs b/test/web/mastodon_api/mastodon_api_controller_test.exs
index f4902d043..24e5785c0 100644
--- a/test/web/mastodon_api/mastodon_api_controller_test.exs
+++ b/test/web/mastodon_api/mastodon_api_controller_test.exs
@@ -3698,7 +3698,7 @@ test "returns 404 when poll is private and not available for user", %{conn: conn
         build_conn()
         |> assign(:user, user)
 
-      [conn: conn, activity: activity]
+      [conn: conn, activity: activity, user: user]
     end
 
     test "returns users who have favorited the status", %{conn: conn, activity: activity} do
@@ -3758,6 +3758,32 @@ test "does not fail on an unauthenticated request", %{conn: conn, activity: acti
       [%{"id" => id}] = response
       assert id == other_user.id
     end
+
+    test "requires authentification for private posts", %{conn: conn, user: user} do
+      other_user = insert(:user)
+
+      {:ok, activity} =
+        CommonAPI.post(user, %{
+          "status" => "@#{other_user.nickname} wanna get some #cofe together?",
+          "visibility" => "direct"
+        })
+
+      {:ok, _, _} = CommonAPI.favorite(activity.id, other_user)
+
+      conn
+      |> assign(:user, nil)
+      |> get("/api/v1/statuses/#{activity.id}/favourited_by")
+      |> json_response(404)
+
+      response =
+        build_conn()
+        |> assign(:user, other_user)
+        |> get("/api/v1/statuses/#{activity.id}/favourited_by")
+        |> json_response(200)
+
+      [%{"id" => id}] = response
+      assert id == other_user.id
+    end
   end
 
   describe "GET /api/v1/statuses/:id/reblogged_by" do
@@ -3769,7 +3795,7 @@ test "does not fail on an unauthenticated request", %{conn: conn, activity: acti
         build_conn()
         |> assign(:user, user)
 
-      [conn: conn, activity: activity]
+      [conn: conn, activity: activity, user: user]
     end
 
     test "returns users who have reblogged the status", %{conn: conn, activity: activity} do
@@ -3829,6 +3855,29 @@ test "does not fail on an unauthenticated request", %{conn: conn, activity: acti
       [%{"id" => id}] = response
       assert id == other_user.id
     end
+
+    test "requires authentification for private posts", %{conn: conn, user: user} do
+      other_user = insert(:user)
+
+      {:ok, activity} =
+        CommonAPI.post(user, %{
+          "status" => "@#{other_user.nickname} wanna get some #cofe together?",
+          "visibility" => "direct"
+        })
+
+      conn
+      |> assign(:user, nil)
+      |> get("/api/v1/statuses/#{activity.id}/reblogged_by")
+      |> json_response(404)
+
+      response =
+        build_conn()
+        |> assign(:user, other_user)
+        |> get("/api/v1/statuses/#{activity.id}/reblogged_by")
+        |> json_response(200)
+
+      assert [] == response
+    end
   end
 
   describe "POST /auth/password, with valid parameters" do