diff --git a/releasenotes/source/index.rst b/releasenotes/source/index.rst
index d8702f9..21f414e 100644
--- a/releasenotes/source/index.rst
+++ b/releasenotes/source/index.rst
@@ -6,6 +6,7 @@
    :maxdepth: 1
 
    unreleased
+   v26.0.0
    v24.0.0
    v23.0.0
    v22.1.0
diff --git a/releasenotes/source/v26.0.0.rst b/releasenotes/source/v26.0.0.rst
new file mode 100644
index 0000000..4161f89
--- /dev/null
+++ b/releasenotes/source/v26.0.0.rst
@@ -0,0 +1,5 @@
+=====================
+v26.0.0 Release Notes
+=====================
+.. release-notes:: 26.0.0 Release Notes
+   :version: 26.0.0
diff --git a/tempest/scenario/manager.py b/tempest/scenario/manager.py
index f369d5d..ce13166 100644
--- a/tempest/scenario/manager.py
+++ b/tempest/scenario/manager.py
@@ -741,14 +741,12 @@
     def nova_volume_detach(self, server, volume):
         """Compute volume detach
 
-        This utility detaches volume from compute and check whether the
-        volume status is 'available' state, and if not, an exception
-        will be thrown.
+        This utility detaches the volume from the server and checks whether the
+        volume attachment has been removed from Nova.
         """
         self.servers_client.detach_volume(server['id'], volume['id'])
-        waiters.wait_for_volume_resource_status(self.volumes_client,
-                                                volume['id'], 'available')
-        volume = self.volumes_client.show_volume(volume['id'])['volume']
+        waiters.wait_for_volume_attachment_remove_from_server(
+            self.servers_client, server['id'], volume['id'])
 
     def ping_ip_address(self, ip_address, should_succeed=True,
                         ping_timeout=None, mtu=None, server=None):
@@ -1067,12 +1065,19 @@
         def cidr_in_use(cidr, project_id):
             """Check cidr existence
 
-            :returns: True if subnet with cidr already exist in tenant
-                  False else
+            :returns: True if subnet with cidr already exist in tenant or
+                  external False else
             """
-            cidr_in_use = self.os_admin.subnets_client.list_subnets(
+            tenant_subnets = self.os_admin.subnets_client.list_subnets(
                 project_id=project_id, cidr=cidr)['subnets']
-            return len(cidr_in_use) != 0
+            external_nets = self.os_admin.networks_client.list_networks(
+                **{"router:external": True})['networks']
+            external_subnets = []
+            for ext_net in external_nets:
+                external_subnets.extend(
+                    self.os_admin.subnets_client.list_subnets(
+                        network_id=ext_net['id'], cidr=cidr)['subnets'])
+            return len(tenant_subnets + external_subnets) != 0
 
         ip_version = kwargs.pop('ip_version', 4)