diff --git a/account/views/oj.py b/account/views/oj.py
index bc8c9cf3..4aaec7cb 100644
--- a/account/views/oj.py
+++ b/account/views/oj.py
@@ -396,7 +396,7 @@ class ProfileProblemDisplayIDRefreshAPI(APIView):
         ids = list(acm_problems.keys()) + list(oi_problems.keys())
         if not ids:
             return self.success()
-        display_ids = Problem.objects.filter(id__in=ids).values_list("_id", flat=True)
+        display_ids = Problem.objects.filter(id__in=ids, visible=True).values_list("_id", flat=True)
         id_map = dict(zip(ids, display_ids))
         for k, v in acm_problems.items():
             v["_id"] = id_map[k]
diff --git a/contest/views/oj.py b/contest/views/oj.py
index 44adc020..9db09bfc 100644
--- a/contest/views/oj.py
+++ b/contest/views/oj.py
@@ -32,7 +32,7 @@ class ContestAPI(APIView):
         if not id:
             return self.error("Invalid parameter, id is required")
         try:
-            contest = Contest.objects.get(id=id)
+            contest = Contest.objects.get(id=id, visible=True)
         except Contest.DoesNotExist:
             return self.error("Contest does not exist")
         data = ContestSerializer(contest).data
@@ -107,7 +107,7 @@ class ContestRankAPI(APIView):
     @check_contest_permission(check_type="ranks")
     def get(self, request):
         force_refresh = request.GET.get("force_refresh")
-        is_contest_admin = request.user.is_contest_admin(self.contest)
+        is_contest_admin = request.user.is_authenticated() and request.user.is_contest_admin(self.contest)
         if self.contest.rule_type == ContestRuleType.OI:
             serializer = OIContestRankSerializer
         else:
diff --git a/submission/views/oj.py b/submission/views/oj.py
index 3c035015..5d6351b0 100644
--- a/submission/views/oj.py
+++ b/submission/views/oj.py
@@ -51,7 +51,7 @@ class SubmissionAPI(APIView):
         hide_id = False
         if data.get("contest_id"):
             try:
-                contest = Contest.objects.get(id=data["contest_id"])
+                contest = Contest.objects.get(id=data["contest_id"], visible=True)
             except Contest.DoesNotExist:
                 return self.error("Contest doesn't exist.")
             if contest.status == ContestStatus.CONTEST_ENDED: