diff --git a/app/models/ext_management_system.rb b/app/models/ext_management_system.rb
index 930f5230df3e..1b4e6adab0c9 100644
--- a/app/models/ext_management_system.rb
+++ b/app/models/ext_management_system.rb
@@ -22,17 +22,15 @@ def self.leaf_subclasses
   end
 
   def self.supported_subclasses
-    subclasses.flat_map do |s|
-      s.subclasses.empty? ? s : s.supported_subclasses
-    end
+    leaf_subclasses.select(&:supported?)
+  end
+
+  def self.supported?
+    Vmdb::PermissionStores.instance.supported_ems_type?(ems_type)
   end
 
   def self.supported_types_and_descriptions_hash
-    supported_subclasses.each_with_object({}) do |klass, hash|
-      if Vmdb::PermissionStores.instance.supported_ems_type?(klass.ems_type)
-        hash[klass.ems_type] = klass.description
-      end
-    end
+    supported_subclasses.each_with_object({}) { |klass, hash| hash[klass.ems_type] = klass.description }
   end
 
   def self.api_allowed_attributes
diff --git a/app/models/service_template.rb b/app/models/service_template.rb
index 07be67c543bb..5dac71d1f23b 100644
--- a/app/models/service_template.rb
+++ b/app/models/service_template.rb
@@ -104,7 +104,7 @@ def self.with_additional_tenants
   end
 
   def self.catalog_item_types
-    ci_types = Set.new(Rbac.filtered(ExtManagementSystem.all).flat_map(&:supported_catalog_types))
+    ci_types = Set.new(Rbac.filtered(ExtManagementSystem.supported_subclasses).flat_map(&:supported_catalog_types))
     ci_types.add('generic_orchestration') if Rbac.filtered(OrchestrationTemplate).exists?
     ci_types.add('generic')
     CATALOG_ITEM_TYPES.each.with_object({}) do |(key, description), hash|