diff --git a/sapl/base/templatetags/menus.py b/sapl/base/templatetags/menus.py
index 0c3f54ca9..65ecdcfec 100644
--- a/sapl/base/templatetags/menus.py
+++ b/sapl/base/templatetags/menus.py
@@ -183,17 +183,21 @@ def resolve_urls_inplace(menu, pk, rm, context):
                     as funcionalidades diretas do MasterDetailCrud, como:
                     - visualização de detalhes, adição, edição, remoção.
                     """
-                    if 'view' in context:
-                        view = context['view']
-                        if hasattr(view, '__class__') and\
-                                hasattr(view.__class__, 'crud'):
-                            urls = view.__class__.crud.get_urls()
-                            for u in urls:
-                                if (u.name == url_name or
-                                        'urls_extras' in menu and
-                                        u.name in menu['urls_extras']):
-                                    menu['active'] = 'active'
-                                    break
+                    try:
+                        if 'view' in context:
+                            view = context['view']
+                            if hasattr(view, 'crud'):
+                                urls = view.crud.get_urls()
+                                for u in urls:
+                                    if (u.name == url_name or
+                                            'urls_extras' in menu and
+                                            u.name in menu['urls_extras']):
+                                        menu['active'] = 'active'
+                                        break
+                    except:
+                        url_active = menu.get('url', '')
+                        logger.warning(
+                            f'Não foi possível definir se url {url_active} é a url ativa.')
         elif 'check_permission' in menu and not context[
                 'request'].user.has_perm(menu['check_permission']):
             menu['active'] = ''
diff --git a/sapl/crud/base.py b/sapl/crud/base.py
index 94637d9d7..5dbc713dc 100644
--- a/sapl/crud/base.py
+++ b/sapl/crud/base.py
@@ -263,18 +263,18 @@ class CrudBaseMixin(CrispyLayoutFormMixin):
             self.model_name_set = getattr(
                 obj.model, obj.model_set).field.model._meta.model_name
 
-        if hasattr(self, 'permission_required') and self.permission_required:
-            if hasattr(obj, 'public'):
-                self.permission_required = list(
-                    set(self.permission_required) - set(obj.public))
-            else:
-                obj.public = []
+        if not hasattr(obj, 'public'):
+            obj.public = []
 
-            self.permission_required = tuple((
-                self.permission(pr) for pr in self.permission_required))
+        if hasattr(self, 'permission_required') and self.permission_required:
 
-        else:
-            obj.public = []
+            self.permission_required = tuple(
+                (
+                    self.permission(pr) for pr in (
+                        set(self.permission_required) - set(obj.public)
+                    )
+                )
+            )
 
     @classmethod
     def url_name(cls, suffix):
@@ -460,7 +460,8 @@ class CrudListView(PermissionRequiredContainerCrudMixin, ListView):
             # URL padrão para primeira coluna da listagem
             url = self.resolve_url(
                 ACTION_DETAIL, args=(obj.id,)) if i == 0 else None
-            # gera URL para matéria a partir de fk_urlify_for_list em layouts.yaml
+            # gera URL para matéria a partir de fk_urlify_for_list em
+            # layouts.yaml
             if i > 0 and func is not None:
                 url = getattr(self, func)(obj, name)[0]
 
@@ -495,7 +496,7 @@ class CrudListView(PermissionRequiredContainerCrudMixin, ListView):
                         if m:
                             ss = get_field_display(m, n[-1])[1]
                             ss = (
-                                    ('<br>' if '<ul>' in ss else ' - ') + ss) \
+                                ('<br>' if '<ul>' in ss else ' - ') + ss) \
                                 if ss and j != 0 and s else ss
                     except:
                         pass
@@ -947,6 +948,8 @@ class CrudDeleteView(PermissionRequiredContainerCrudMixin,
 
 
 class Crud:
+    __abstract__ = True
+
     BaseMixin = CrudBaseMixin
     ListView = CrudListView
     CreateView = CrudCreateView
@@ -962,15 +965,32 @@ class Crud:
     def get_urls(cls):
 
         def _add_base(view):
-            if view:
 
-                class CrudViewWithBase(cls.BaseMixin, view):
-                    model = cls.model
-                    help_topic = cls.help_topic
-                    crud = cls
+            if not view:
+                return
 
-                CrudViewWithBase.__name__ = view.__name__
-                return CrudViewWithBase
+            if not cls.__abstract__:
+                return view
+
+            pr = set()
+            if hasattr(view, 'permission_required') and \
+                    view.permission_required and \
+                    hasattr(cls, 'public') and \
+                    cls.public:
+
+                #print(view.permission_required, view)
+                #print(cls.public, cls)
+
+                pr = set(view.permission_required) - set(cls.public)
+
+            class CrudViewWithBase(cls.BaseMixin, view):
+                permission_required = tuple(pr)
+                model = cls.model
+                help_topic = cls.help_topic
+                crud = cls
+
+            CrudViewWithBase.__name__ = view.__name__
+            return CrudViewWithBase
 
         CrudListView = _add_base(cls.ListView)
         CrudCreateView = _add_base(cls.CreateView)
@@ -978,6 +998,21 @@ class Crud:
         CrudUpdateView = _add_base(cls.UpdateView)
         CrudDeleteView = _add_base(cls.DeleteView)
 
+        cruds = CrudListView, CrudCreateView, CrudDetailView, CrudUpdateView, CrudDeleteView
+
+        if cls.__abstract__:
+            class CRUD(cls):
+                __abstract__ = False
+                ListView = CrudListView
+                CreateView = CrudCreateView
+                DetailView = CrudDetailView
+                UpdateView = CrudUpdateView
+                DeleteView = CrudDeleteView
+
+            for c in cruds:
+                if c:
+                    c.crud = CRUD
+
         cruds_base = [
             (CrudListView.get_url_regex()
              if CrudListView else None, CrudListView, ACTION_LIST),