Add back access check

judge/views/submission.py

@@ -753,6 +753,11 @@ class UserContestSubmissions(ForceContestMixin, UserProblemSubmissions):
             self.contest.name,
         )
 
+    def access_check(self, request):
+        super(UserContestSubmissions, self).access_check(request)
+        if not self.contest.users.filter(user_id=self.profile.id).exists():
+            raise Http404()
+
     def get_content_title(self):
         if self.problem.is_accessible_by(self.request.user):
             return format_html(