diff --git a/lib/private/Share20/Manager.php b/lib/private/Share20/Manager.php
index 35166c37ee3..a84481730c4 100644
--- a/lib/private/Share20/Manager.php
+++ b/lib/private/Share20/Manager.php
@@ -217,6 +217,17 @@ class Manager implements IManager {
 			throw new \InvalidArgumentException($this->l->t('Valid permissions are required for sharing'));
 		}
 
+		// Permissions must be valid
+		if ($share->getPermissions() < 0 || $share->getPermissions() > \OCP\Constants::PERMISSION_ALL) {
+			throw new \InvalidArgumentException($this->l->t('Valid permissions are required for sharing'));
+		}
+
+		// Single file shares should never have delete or create permissions
+		if (($share->getNode() instanceof File)
+			&& (($share->getPermissions() & (\OCP\Constants::PERMISSION_CREATE | \OCP\Constants::PERMISSION_DELETE)) !== 0)) {
+			throw new \InvalidArgumentException($this->l->t('File shares cannot have create or delete permissions'));
+		}
+
 		$permissions = 0;
 		$nodesForUser = $userFolder->getById($share->getNodeId());
 		foreach ($nodesForUser as $node) {
diff --git a/tests/lib/Share20/ManagerTest.php b/tests/lib/Share20/ManagerTest.php
index 6df97423989..8b8d6ea4e65 100644
--- a/tests/lib/Share20/ManagerTest.php
+++ b/tests/lib/Share20/ManagerTest.php
@@ -893,10 +893,9 @@ class ManagerTest extends \Test\TestCase {
 		$mount = $this->createMock(MoveableMount::class);
 		$limitedPermssions->method('getMountPoint')->willReturn($mount);
 
-
-		$data[] = [$this->createShare(null, IShare::TYPE_USER, $limitedPermssions, $user2, $user0, $user0, 31, null, null), 'Cannot increase permissions of path', true];
+		// increase permissions of a re-share
 		$data[] = [$this->createShare(null, IShare::TYPE_GROUP, $limitedPermssions, $group0, $user0, $user0, 17, null, null), 'Cannot increase permissions of path', true];
-		$data[] = [$this->createShare(null, IShare::TYPE_LINK, $limitedPermssions, null, $user0, $user0, 3, null, null), 'Cannot increase permissions of path', true];
+		$data[] = [$this->createShare(null, IShare::TYPE_USER, $limitedPermssions, $user2, $user0, $user0, 3, null, null), 'Cannot increase permissions of path', true];
 
 		$nonMovableStorage = $this->createMock(IStorage::class);
 		$nonMovableStorage->method('instanceOfStorage')
@@ -927,6 +926,20 @@ class ManagerTest extends \Test\TestCase {
 		$data[] = [$this->createShare(null, IShare::TYPE_GROUP, $rootFolder, $group0, $user0, $user0, 2, null, null), 'You cannot share your root folder', true];
 		$data[] = [$this->createShare(null, IShare::TYPE_LINK, $rootFolder, null, $user0, $user0, 16, null, null), 'You cannot share your root folder', true];
 
+		$allPermssionsFiles = $this->createMock(File::class);
+		$allPermssionsFiles->method('isShareable')->willReturn(true);
+		$allPermssionsFiles->method('getPermissions')->willReturn(\OCP\Constants::PERMISSION_ALL);
+		$allPermssionsFiles->method('getId')->willReturn(187);
+		$allPermssionsFiles->method('getOwner')
+			->willReturn($owner);
+		$allPermssionsFiles->method('getStorage')
+			->willReturn($storage);
+
+		// test invalid CREATE or DELETE permissions
+		$data[] = [$this->createShare(null, IShare::TYPE_USER, $allPermssionsFiles, $user2, $user0, $user0, \OCP\Constants::PERMISSION_ALL, null, null), 'File shares cannot have create or delete permissions', true];
+		$data[] = [$this->createShare(null, IShare::TYPE_GROUP, $allPermssionsFiles, $group0, $user0, $user0, \OCP\Constants::PERMISSION_READ | \OCP\Constants::PERMISSION_CREATE, null, null), 'File shares cannot have create or delete permissions', true];
+		$data[] = [$this->createShare(null, IShare::TYPE_LINK, $allPermssionsFiles, null, $user0, $user0, \OCP\Constants::PERMISSION_READ | \OCP\Constants::PERMISSION_DELETE, null, null), 'File shares cannot have create or delete permissions', true];
+
 		$allPermssions = $this->createMock(Folder::class);
 		$allPermssions->method('isShareable')->willReturn(true);
 		$allPermssions->method('getPermissions')->willReturn(\OCP\Constants::PERMISSION_ALL);
@@ -939,6 +952,12 @@ class ManagerTest extends \Test\TestCase {
 		$data[] = [$this->createShare(null, IShare::TYPE_USER, $allPermssions, $user2, $user0, $user0, 30, null, null), 'Shares need at least read permissions', true];
 		$data[] = [$this->createShare(null, IShare::TYPE_GROUP, $allPermssions, $group0, $user0, $user0, 2, null, null), 'Shares need at least read permissions', true];
 
+		// test invalid permissions
+		$data[] = [$this->createShare(null, IShare::TYPE_USER, $allPermssions, $user2, $user0, $user0, 32, null, null), 'Valid permissions are required for sharing', true];
+		$data[] = [$this->createShare(null, IShare::TYPE_GROUP, $allPermssions, $group0, $user0, $user0, 63, null, null), 'Valid permissions are required for sharing', true];
+		$data[] = [$this->createShare(null, IShare::TYPE_LINK, $allPermssions, null, $user0, $user0, -1, null, null), 'Valid permissions are required for sharing', true];
+
+		// working shares
 		$data[] = [$this->createShare(null, IShare::TYPE_USER, $allPermssions, $user2, $user0, $user0, 31, null, null), null, false];
 		$data[] = [$this->createShare(null, IShare::TYPE_GROUP, $allPermssions, $group0, $user0, $user0, 3, null, null), null, false];
 		$data[] = [$this->createShare(null, IShare::TYPE_LINK, $allPermssions, null, $user0, $user0, 17, null, null), null, false];
@@ -2406,8 +2425,9 @@ class ManagerTest extends \Test\TestCase {
 	}
 
 	public function testCreateShareUser(): void {
+		/** @var Manager&MockObject $manager */
 		$manager = $this->createManagerMock()
-			->setMethods(['canShare', 'generalCreateChecks', 'userCreateChecks', 'pathCreateChecks'])
+			->onlyMethods(['canShare', 'generalCreateChecks', 'userCreateChecks', 'pathCreateChecks'])
 			->getMock();
 
 		$shareOwner = $this->createMock(IUser::class);