diff --git a/application/src/main/java/org/thingsboard/server/controller/AlarmController.java b/application/src/main/java/org/thingsboard/server/controller/AlarmController.java
index fd91abed3a..26e61a495a 100644
--- a/application/src/main/java/org/thingsboard/server/controller/AlarmController.java
+++ b/application/src/main/java/org/thingsboard/server/controller/AlarmController.java
@@ -30,6 +30,7 @@ import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestController;
 import org.thingsboard.server.common.data.StringUtils;
+import org.thingsboard.server.common.data.User;
 import org.thingsboard.server.common.data.alarm.Alarm;
 import org.thingsboard.server.common.data.alarm.AlarmInfo;
 import org.thingsboard.server.common.data.alarm.AlarmQuery;
@@ -47,6 +48,7 @@ import org.thingsboard.server.common.data.page.TimePageLink;
 import org.thingsboard.server.queue.util.TbCoreComponent;
 import org.thingsboard.server.service.entitiy.alarm.TbAlarmService;
 import org.thingsboard.server.service.security.model.SecurityUser;
+import org.thingsboard.server.service.security.model.UserPrincipal;
 import org.thingsboard.server.service.security.permission.Operation;
 import org.thingsboard.server.service.security.permission.Resource;
 
@@ -204,12 +206,13 @@ public class AlarmController extends BaseController {
         AlarmId alarmId = new AlarmId(toUUID(strAlarmId));
         UserId assigneeId = new UserId(UUID.fromString(strAssigneeId));
         Alarm alarm = checkAlarmId(alarmId, Operation.WRITE);
-        if (!getCurrentUser().getId().equals(assigneeId)) {
-            try {
-                checkEntityId(alarm.getOriginator(), Operation.WRITE, new SecurityUser(assigneeId));
-            } catch (Exception e) {
-                throw new ThingsboardException("Assignee user doesn't have permission for alarm originator", ThingsboardErrorCode.PERMISSION_DENIED);
-            }
+        User assigneeUser = userService.findUserById(getTenantId(), assigneeId);
+
+        SecurityUser assigneeSecurityUser = new SecurityUser(assigneeUser, false, null);
+        try {
+            checkEntityId(alarm.getOriginator(), Operation.WRITE, assigneeSecurityUser);
+        } catch (Exception e) {
+            throw new ThingsboardException("Assignee user doesn't have permission for alarm originator", ThingsboardErrorCode.PERMISSION_DENIED);
         }
         tbAlarmService.assign(alarm, getCurrentUser(), assigneeId).get();
     }
diff --git a/application/src/test/java/org/thingsboard/server/controller/AbstractWebTest.java b/application/src/test/java/org/thingsboard/server/controller/AbstractWebTest.java
index 9ea269918e..e94a0646d9 100644
--- a/application/src/test/java/org/thingsboard/server/controller/AbstractWebTest.java
+++ b/application/src/test/java/org/thingsboard/server/controller/AbstractWebTest.java
@@ -154,6 +154,7 @@ public abstract class AbstractWebTest extends AbstractInMemoryStorageTest {
     protected TenantId differentTenantId;
     protected CustomerId differentCustomerId;
     protected UserId customerUserId;
+    protected UserId differentCustomerUserId;
 
     @SuppressWarnings("rawtypes")
     private HttpMessageConverter mappingJackson2HttpMessageConverter;
@@ -324,7 +325,8 @@ public abstract class AbstractWebTest extends AbstractInMemoryStorageTest {
             differentCustomerUser.setCustomerId(savedDifferentCustomer.getId());
             differentCustomerUser.setEmail(DIFFERENT_CUSTOMER_USER_EMAIL);
 
-            createUserAndLogin(differentCustomerUser, DIFFERENT_CUSTOMER_USER_PASSWORD);
+            differentCustomerUser = createUserAndLogin(differentCustomerUser, DIFFERENT_CUSTOMER_USER_PASSWORD);
+            differentCustomerUserId = differentCustomerUser.getId();
         }
     }
 
diff --git a/application/src/test/java/org/thingsboard/server/controller/BaseAlarmControllerTest.java b/application/src/test/java/org/thingsboard/server/controller/BaseAlarmControllerTest.java
index 05b6f15c61..cc793d8984 100644
--- a/application/src/test/java/org/thingsboard/server/controller/BaseAlarmControllerTest.java
+++ b/application/src/test/java/org/thingsboard/server/controller/BaseAlarmControllerTest.java
@@ -28,6 +28,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Primary;
 import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.web.servlet.ResultActions;
 import org.thingsboard.common.util.JacksonUtil;
 import org.thingsboard.server.common.data.Device;
 import org.thingsboard.server.common.data.EntityType;
@@ -364,6 +365,18 @@ public abstract class BaseAlarmControllerTest extends AbstractControllerTest {
                 tenantId, customerId, tenantAdminUserId, TENANT_ADMIN_EMAIL, ActionType.ALARM_ASSIGN);
     }
 
+    @Test
+    public void testAssignAlarmViaDifferentTenant() throws Exception {
+        loginTenantAdmin();
+        Alarm alarm = createAlarm(TEST_ALARM_TYPE);
+
+        loginDifferentTenant();
+
+        Mockito.reset(tbClusterService, auditLogService);
+
+        doPost("/api/alarm/" + alarm.getId() + "/assign/" + tenantAdminUserId.getId()).andExpect(status().isForbidden());
+    }
+
     @Test
     public void testReassignAlarm() throws Exception {
         loginTenantAdmin();
@@ -426,6 +439,38 @@ public abstract class BaseAlarmControllerTest extends AbstractControllerTest {
                 tenantId, customerId, tenantAdminUserId, TENANT_ADMIN_EMAIL, ActionType.ALARM_UNASSIGN);
     }
 
+    @Test
+    public void testUnassignTenantAlarmViaCustomer() throws Exception {
+        loginTenantAdmin();
+        Alarm alarm = createAlarm(TEST_ALARM_TYPE);
+        Mockito.reset(tbClusterService, auditLogService);
+        long beforeAssignmentTs = System.currentTimeMillis();
+
+        doPost("/api/alarm/" + alarm.getId() + "/assign/" + tenantAdminUserId.getId()).andExpect(status().isOk());
+        Alarm foundAlarm = doGet("/api/alarm/" + alarm.getId(), Alarm.class);
+        Assert.assertNotNull(foundAlarm);
+        Assert.assertEquals(tenantAdminUserId, foundAlarm.getAssigneeId());
+        Assert.assertTrue(foundAlarm.getAssignTs() > beforeAssignmentTs && foundAlarm.getAssignTs() < System.currentTimeMillis());
+
+        testNotifyEntityAllOneTime(foundAlarm, foundAlarm.getId(), foundAlarm.getOriginator(),
+                tenantId, customerId, tenantAdminUserId, TENANT_ADMIN_EMAIL, ActionType.ALARM_ASSIGN);
+
+        logout();
+        loginCustomerUser();
+
+        Mockito.reset(tbClusterService, auditLogService);
+        beforeAssignmentTs = System.currentTimeMillis();
+
+        doDelete("/api/alarm/" + alarm.getId() + "/assign").andExpect(status().isOk());
+        foundAlarm = doGet("/api/alarm/" + alarm.getId(), Alarm.class);
+        Assert.assertNotNull(foundAlarm);
+        Assert.assertNull(foundAlarm.getAssigneeId());
+        Assert.assertTrue(foundAlarm.getAssignTs() > beforeAssignmentTs && foundAlarm.getAssignTs() < System.currentTimeMillis());
+
+        testNotifyEntityAllOneTime(foundAlarm, foundAlarm.getId(), foundAlarm.getOriginator(),
+                tenantId, customerId, customerUserId, CUSTOMER_USER_EMAIL, ActionType.ALARM_UNASSIGN);
+    }
+
     @Test
     public void testFindAlarmsViaCustomerUser() throws Exception {
         loginCustomerUser();