diff --git a/.github/linters/.tflint_workspaces.hcl b/.github/linters/.tflint_workspaces.hcl
index bfb0c85e20..86862b463b 100644
--- a/.github/linters/.tflint_workspaces.hcl
+++ b/.github/linters/.tflint_workspaces.hcl
@@ -7,6 +7,8 @@ config {
 
 plugin "azurerm" {
     enabled = true
+    version = "0.30.0"
+    source  = "github.com/terraform-linters/tflint-ruleset-azurerm"
 }
 
 rule "azurerm_resource_missing_tags" {
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e9da0f3fda..e89223aeea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 * Sonatype Nexus shared service now requires explicit EULA acceptance (`accept_nexus_eula: true`) when deploying. This ensures compliance with Sonatype Nexus Community Edition licensing. ([#4842](https://github.com/microsoft/AzureTRE/issues/4842))
 
 ENHANCEMENTS:
+* Specify default_outbound_access_enabled = false setting for all subnets ([#4757](https://github.com/microsoft/AzureTRE/pull/4757))
 * Add interactive browser login method to TRE CLI for easier authentication ([#4856](https://github.com/microsoft/AzureTRE/issues/4856))
 * Harden security of the app gateway. ([#4863](https://github.com/microsoft/AzureTRE/pull/4863))
 * Pass OIDC vars directly to the devcontainer ([#4871](https://github.com/microsoft/AzureTRE/issues/4871))
diff --git a/core/terraform/network/network.tf b/core/terraform/network/network.tf
index 9e85be11ea..7b81bb1fa9 100644
--- a/core/terraform/network/network.tf
+++ b/core/terraform/network/network.tf
@@ -7,15 +7,17 @@ resource "azurerm_virtual_network" "core" {
   lifecycle { ignore_changes = [tags] }
 
   subnet {
-    name             = "AzureBastionSubnet"
-    address_prefixes = [local.bastion_subnet_address_prefix]
-    security_group   = azurerm_network_security_group.bastion.id
+    name                            = "AzureBastionSubnet"
+    address_prefixes                = [local.bastion_subnet_address_prefix]
+    security_group                  = azurerm_network_security_group.bastion.id
+    default_outbound_access_enabled = false
   }
 
   subnet {
-    name             = "AzureFirewallSubnet"
-    address_prefixes = [local.firewall_subnet_address_space]
-    route_table_id   = var.firewall_force_tunnel_ip != "" ? azurerm_route_table.fw_tunnel_rt[0].id : null
+    name                            = "AzureFirewallSubnet"
+    address_prefixes                = [local.firewall_subnet_address_space]
+    route_table_id                  = var.firewall_force_tunnel_ip != "" ? azurerm_route_table.fw_tunnel_rt[0].id : null
+    default_outbound_access_enabled = false
   }
 
   subnet {
@@ -24,6 +26,7 @@ resource "azurerm_virtual_network" "core" {
     private_endpoint_network_policies             = "Disabled"
     private_link_service_network_policies_enabled = true
     security_group                                = azurerm_network_security_group.app_gw.id
+    default_outbound_access_enabled               = false
   }
 
   subnet {
@@ -33,6 +36,7 @@ resource "azurerm_virtual_network" "core" {
     private_link_service_network_policies_enabled = true
     security_group                                = azurerm_network_security_group.default_rules.id
     route_table_id                                = azurerm_route_table.rt.id
+    default_outbound_access_enabled               = false
 
     delegation {
       name = "delegation"
@@ -50,6 +54,7 @@ resource "azurerm_virtual_network" "core" {
     private_endpoint_network_policies = "Disabled"
     security_group                    = azurerm_network_security_group.default_rules.id
     route_table_id                    = azurerm_route_table.rt.id
+    default_outbound_access_enabled   = false
   }
 
   subnet {
@@ -58,6 +63,7 @@ resource "azurerm_virtual_network" "core" {
     private_endpoint_network_policies = "Disabled"
     security_group                    = azurerm_network_security_group.default_rules.id
     route_table_id                    = azurerm_route_table.rt.id
+    default_outbound_access_enabled   = false
   }
 
   subnet {
@@ -66,6 +72,7 @@ resource "azurerm_virtual_network" "core" {
     private_endpoint_network_policies = "Disabled"
     security_group                    = azurerm_network_security_group.default_rules.id
     route_table_id                    = azurerm_route_table.rt.id
+    default_outbound_access_enabled   = false
 
     delegation {
       name = "delegation"
@@ -84,7 +91,7 @@ resource "azurerm_virtual_network" "core" {
     address_prefixes                  = [local.airlock_notifications_subnet_address_prefix]
     private_endpoint_network_policies = "Disabled"
     security_group                    = azurerm_network_security_group.default_rules.id
-
+    default_outbound_access_enabled   = false
     delegation {
       name = "delegation"
 
@@ -102,6 +109,7 @@ resource "azurerm_virtual_network" "core" {
     private_endpoint_network_policies = "Disabled"
     security_group                    = azurerm_network_security_group.default_rules.id
     route_table_id                    = azurerm_route_table.rt.id
+    default_outbound_access_enabled   = false
   }
 
   subnet {
@@ -110,13 +118,15 @@ resource "azurerm_virtual_network" "core" {
     private_endpoint_network_policies = "Disabled"
     security_group                    = azurerm_network_security_group.default_rules.id
     route_table_id                    = azurerm_route_table.rt.id
+    default_outbound_access_enabled   = false
 
     service_endpoints = ["Microsoft.ServiceBus"]
   }
 
   subnet {
-    name             = "AzureFirewallManagementSubnet"
-    address_prefixes = [local.firewall_management_subnet_address_prefix]
+    name                            = "AzureFirewallManagementSubnet"
+    address_prefixes                = [local.firewall_management_subnet_address_prefix]
+    default_outbound_access_enabled = false
   }
 }
 
diff --git a/templates/shared_services/databricks-auth/porter.yaml b/templates/shared_services/databricks-auth/porter.yaml
index fc7ae06217..f7d34be8cc 100644
--- a/templates/shared_services/databricks-auth/porter.yaml
+++ b/templates/shared_services/databricks-auth/porter.yaml
@@ -1,7 +1,7 @@
 ---
 schemaVersion: 1.0.0
 name: tre-shared-service-databricks-private-auth
-version: 0.1.13
+version: 0.1.14
 description: "An Azure TRE shared service for Azure Databricks authentication."
 registry: azuretre
 dockerfile: Dockerfile.tmpl
diff --git a/templates/shared_services/databricks-auth/terraform/network.tf b/templates/shared_services/databricks-auth/terraform/network.tf
index 90cc9d0304..705d2275cb 100644
--- a/templates/shared_services/databricks-auth/terraform/network.tf
+++ b/templates/shared_services/databricks-auth/terraform/network.tf
@@ -9,10 +9,11 @@ resource "azurerm_virtual_network" "ws" {
 }
 
 resource "azurerm_subnet" "host" {
-  name                 = local.host_subnet_name
-  resource_group_name  = local.resource_group_name
-  virtual_network_name = azurerm_virtual_network.ws.name
-  address_prefixes     = [local.host_subnet_address_space]
+  name                            = local.host_subnet_name
+  resource_group_name             = local.resource_group_name
+  virtual_network_name            = azurerm_virtual_network.ws.name
+  address_prefixes                = [local.host_subnet_address_space]
+  default_outbound_access_enabled = false
 
   delegation {
     name = "db-host-vnet-integration"
@@ -29,10 +30,11 @@ resource "azurerm_subnet" "host" {
 }
 
 resource "azurerm_subnet" "container" {
-  name                 = local.container_subnet_name
-  resource_group_name  = local.resource_group_name
-  virtual_network_name = azurerm_virtual_network.ws.name
-  address_prefixes     = [local.container_subnet_address_space]
+  name                            = local.container_subnet_name
+  resource_group_name             = local.resource_group_name
+  virtual_network_name            = azurerm_virtual_network.ws.name
+  address_prefixes                = [local.container_subnet_address_space]
+  default_outbound_access_enabled = false
 
   delegation {
     name = "db-container-vnet-integration"
diff --git a/templates/workspace_services/azureml/porter.yaml b/templates/workspace_services/azureml/porter.yaml
index ee98b376ba..d4dd7164de 100644
--- a/templates/workspace_services/azureml/porter.yaml
+++ b/templates/workspace_services/azureml/porter.yaml
@@ -1,7 +1,7 @@
 ---
 schemaVersion: 1.0.0
 name: tre-service-azureml
-version: 1.1.2
+version: 1.1.3
 description: "An Azure TRE service for Azure Machine Learning"
 registry: azuretre
 dockerfile: Dockerfile.tmpl
diff --git a/templates/workspace_services/azureml/terraform/network.tf b/templates/workspace_services/azureml/terraform/network.tf
index 4e822a60c1..836fd3a3f1 100644
--- a/templates/workspace_services/azureml/terraform/network.tf
+++ b/templates/workspace_services/azureml/terraform/network.tf
@@ -61,10 +61,11 @@ resource "azapi_resource" "aml_service_endpoint_policy" {
 }
 
 resource "azurerm_subnet" "aml" {
-  name                 = "AMLSubnet${local.short_service_id}"
-  virtual_network_name = data.azurerm_virtual_network.ws.name
-  resource_group_name  = data.azurerm_virtual_network.ws.resource_group_name
-  address_prefixes     = [var.address_space]
+  name                            = "AMLSubnet${local.short_service_id}"
+  virtual_network_name            = data.azurerm_virtual_network.ws.name
+  resource_group_name             = data.azurerm_virtual_network.ws.resource_group_name
+  address_prefixes                = [var.address_space]
+  default_outbound_access_enabled = false
 
   # need to be disabled for AML private compute
   private_endpoint_network_policies             = "Disabled"
diff --git a/templates/workspace_services/databricks/porter.yaml b/templates/workspace_services/databricks/porter.yaml
index 8fdffa2db8..e3222da2f5 100644
--- a/templates/workspace_services/databricks/porter.yaml
+++ b/templates/workspace_services/databricks/porter.yaml
@@ -1,7 +1,7 @@
 ---
 schemaVersion: 1.0.0
 name: tre-service-databricks
-version: 1.0.14
+version: 1.0.15
 description: "An Azure TRE service for Azure Databricks."
 registry: azuretre
 dockerfile: Dockerfile.tmpl
diff --git a/templates/workspace_services/databricks/terraform/network.tf b/templates/workspace_services/databricks/terraform/network.tf
index 63edae00d0..366dd0f2d5 100644
--- a/templates/workspace_services/databricks/terraform/network.tf
+++ b/templates/workspace_services/databricks/terraform/network.tf
@@ -88,10 +88,11 @@ resource "azurerm_network_security_group" "nsg" {
 }
 
 resource "azurerm_subnet" "host" {
-  name                 = local.host_subnet_name
-  resource_group_name  = data.azurerm_resource_group.ws.name
-  virtual_network_name = data.azurerm_virtual_network.ws.name
-  address_prefixes     = [local.host_subnet_address_space]
+  name                            = local.host_subnet_name
+  resource_group_name             = data.azurerm_resource_group.ws.name
+  virtual_network_name            = data.azurerm_virtual_network.ws.name
+  address_prefixes                = [local.host_subnet_address_space]
+  default_outbound_access_enabled = false
 
   delegation {
     name = "db-host-vnet-integration"
@@ -108,10 +109,11 @@ resource "azurerm_subnet" "host" {
 }
 
 resource "azurerm_subnet" "container" {
-  name                 = local.container_subnet_name
-  resource_group_name  = data.azurerm_resource_group.ws.name
-  virtual_network_name = data.azurerm_virtual_network.ws.name
-  address_prefixes     = [local.container_subnet_address_space]
+  name                            = local.container_subnet_name
+  resource_group_name             = data.azurerm_resource_group.ws.name
+  virtual_network_name            = data.azurerm_virtual_network.ws.name
+  address_prefixes                = [local.container_subnet_address_space]
+  default_outbound_access_enabled = false
 
   delegation {
     name = "db-container-vnet-integration"
diff --git a/templates/workspace_services/ohdsi/porter.yaml b/templates/workspace_services/ohdsi/porter.yaml
index 64789cd14e..a2cf1f71d6 100644
--- a/templates/workspace_services/ohdsi/porter.yaml
+++ b/templates/workspace_services/ohdsi/porter.yaml
@@ -1,7 +1,7 @@
 ---
 schemaVersion: 1.0.0
 name: tre-workspace-service-ohdsi
-version: 0.3.5
+version: 0.3.6
 description: "An OHDSI workspace service"
 registry: azuretre
 dockerfile: Dockerfile.tmpl
diff --git a/templates/workspace_services/ohdsi/terraform/atlas_database.tf b/templates/workspace_services/ohdsi/terraform/atlas_database.tf
index 6dcd6c4b3a..7d26918705 100644
--- a/templates/workspace_services/ohdsi/terraform/atlas_database.tf
+++ b/templates/workspace_services/ohdsi/terraform/atlas_database.tf
@@ -100,10 +100,11 @@ resource "azurerm_network_security_group" "postgres" {
 }
 
 resource "azurerm_subnet" "postgres" {
-  name                 = "PostgreSQLSubnet${local.short_service_id}"
-  virtual_network_name = data.azurerm_virtual_network.ws.name
-  resource_group_name  = data.azurerm_resource_group.ws.name
-  address_prefixes     = [var.address_space]
+  name                            = "PostgreSQLSubnet${local.short_service_id}"
+  virtual_network_name            = data.azurerm_virtual_network.ws.name
+  resource_group_name             = data.azurerm_resource_group.ws.name
+  address_prefixes                = [var.address_space]
+  default_outbound_access_enabled = false
 
   delegation {
     name = "psql-delegation"
diff --git a/templates/workspaces/base/porter.yaml b/templates/workspaces/base/porter.yaml
index c970a581d9..a71c799ebe 100644
--- a/templates/workspaces/base/porter.yaml
+++ b/templates/workspaces/base/porter.yaml
@@ -1,7 +1,7 @@
 ---
 schemaVersion: 1.0.0
 name: tre-workspace-base
-version: 2.8.1
+version: 2.8.2
 description: "A base Azure TRE workspace"
 dockerfile: Dockerfile.tmpl
 registry: azuretre
diff --git a/templates/workspaces/base/terraform/network/network.tf b/templates/workspaces/base/terraform/network/network.tf
index f743a2aac8..0854668fd3 100644
--- a/templates/workspaces/base/terraform/network/network.tf
+++ b/templates/workspaces/base/terraform/network/network.tf
@@ -16,6 +16,7 @@ resource "azurerm_subnet" "services" {
   # notice that private endpoints do not adhere to NSG rules
   private_endpoint_network_policies             = "Disabled"
   private_link_service_network_policies_enabled = true
+  default_outbound_access_enabled               = false
 }
 
 resource "azurerm_subnet" "webapps" {
@@ -26,6 +27,7 @@ resource "azurerm_subnet" "webapps" {
   # notice that private endpoints do not adhere to NSG rules
   private_endpoint_network_policies             = "Disabled"
   private_link_service_network_policies_enabled = true
+  default_outbound_access_enabled               = false
 
   delegation {
     name = "delegation"