diff --git a/lib/Service/CardService.php b/lib/Service/CardService.php
index 639fa078e..3c6742e1e 100644
--- a/lib/Service/CardService.php
+++ b/lib/Service/CardService.php
@@ -609,8 +609,9 @@ class CardService {
 	public function assignLabel($cardId, $labelId) {
 		$this->cardServiceValidator->check(compact('cardId', 'labelId'));
 
-
 		$this->permissionService->checkPermission($this->cardMapper, $cardId, Acl::PERMISSION_EDIT);
+		$this->permissionService->checkPermission($this->labelMapper, $labelId, Acl::PERMISSION_READ);
+
 		if ($this->boardService->isArchived($this->cardMapper, $cardId)) {
 			throw new StatusException('Operation not allowed. This board is archived.');
 		}
@@ -619,6 +620,9 @@ class CardService {
 			throw new StatusException('Operation not allowed. This card is archived.');
 		}
 		$label = $this->labelMapper->find($labelId);
+		if ($label->getBoardId() !== $this->cardMapper->findBoardId($card->getId())) {
+			throw new StatusException('Operation not allowed. Label does not exist.');
+		}
 		$this->cardMapper->assignLabel($cardId, $labelId);
 		$this->changeHelper->cardChanged($cardId);
 		$this->activityManager->triggerEvent(ActivityManager::DECK_OBJECT_CARD, $card, ActivityManager::SUBJECT_LABEL_ASSIGN, ['label' => $label]);
@@ -640,6 +644,8 @@ class CardService {
 
 
 		$this->permissionService->checkPermission($this->cardMapper, $cardId, Acl::PERMISSION_EDIT);
+		$this->permissionService->checkPermission($this->labelMapper, $labelId, Acl::PERMISSION_READ);
+
 		if ($this->boardService->isArchived($this->cardMapper, $cardId)) {
 			throw new StatusException('Operation not allowed. This board is archived.');
 		}
@@ -648,6 +654,9 @@ class CardService {
 			throw new StatusException('Operation not allowed. This card is archived.');
 		}
 		$label = $this->labelMapper->find($labelId);
+		if ($label->getBoardId() !== $this->cardMapper->findBoardId($card->getId())) {
+			throw new StatusException('Operation not allowed. Label does not exist.');
+		}
 		$this->cardMapper->removeLabel($cardId, $labelId);
 		$this->changeHelper->cardChanged($cardId);
 		$this->activityManager->triggerEvent(ActivityManager::DECK_OBJECT_CARD, $card, ActivityManager::SUBJECT_LABEL_UNASSING, ['label' => $label]);
diff --git a/tests/unit/Service/CardServiceTest.php b/tests/unit/Service/CardServiceTest.php
index f7e8b3a99..73e29093f 100644
--- a/tests/unit/Service/CardServiceTest.php
+++ b/tests/unit/Service/CardServiceTest.php
@@ -258,6 +258,17 @@ class CardServiceTest extends TestCase {
 			->method('find')
 			->willReturn($card, $clonedCard);
 
+		$this->cardMapper->expects($this->any())
+			->method('findBoardId')
+			->willReturn(1234);
+
+		$this->labelMapper->expects($this->any())
+			->method('find')
+			->willReturn(Label::fromRow([
+				'id' => 1,
+				'boardId' => 1234,
+			]));
+
 		// check if users are assigned
 		$this->assignmentService->expects($this->once())
 			->method('assignUser')
@@ -433,8 +444,17 @@ class CardServiceTest extends TestCase {
 	public function testAssignLabel() {
 		$card = new Card();
 		$card->setArchived(false);
+		$card->setId(123);
+		$label = new Label();
+		$label->setBoardId(1);
 		$this->cardMapper->expects($this->once())->method('find')->willReturn($card);
 		$this->cardMapper->expects($this->once())->method('assignLabel');
+		$this->cardMapper->expects($this->once())
+			->method('findBoardId')
+			->willReturn(1);
+		$this->labelMapper->expects($this->once())
+			->method('find')
+			->willReturn($label);
 		$this->cardService->assignLabel(123, 999);
 	}
 
@@ -450,8 +470,17 @@ class CardServiceTest extends TestCase {
 	public function testRemoveLabel() {
 		$card = new Card();
 		$card->setArchived(false);
+		$card->setId(123);
+		$label = new Label();
+		$label->setBoardId(1);
 		$this->cardMapper->expects($this->once())->method('find')->willReturn($card);
 		$this->cardMapper->expects($this->once())->method('removeLabel');
+		$this->cardMapper->expects($this->once())
+			->method('findBoardId')
+			->willReturn(1);
+		$this->labelMapper->expects($this->once())
+			->method('find')
+			->willReturn($label);
 		$this->cardService->removeLabel(123, 999);
 	}