diff --git a/VERSION b/VERSION
index 97cae93..d24bae7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.1.139
+1.1.140
diff --git a/cmd/edgeguard-api/main.go b/cmd/edgeguard-api/main.go
index bbf3536..cdec34c 100644
--- a/cmd/edgeguard-api/main.go
+++ b/cmd/edgeguard-api/main.go
@@ -60,7 +60,7 @@ import (
 	usersvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/users"
 )
 
-var version = "1.1.139"
+var version = "1.1.140"
 
 func main() {
 	addr := os.Getenv("EDGEGUARD_API_ADDR")
diff --git a/cmd/edgeguard-ctl/main.go b/cmd/edgeguard-ctl/main.go
index 6e3c408..fae04ca 100644
--- a/cmd/edgeguard-ctl/main.go
+++ b/cmd/edgeguard-ctl/main.go
@@ -11,7 +11,7 @@ import (
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/setup"
 )
 
-var version = "1.1.139"
+var version = "1.1.140"
 
 const usage = `edgeguard-ctl — EdgeGuard CLI
 
diff --git a/cmd/edgeguard-scheduler/main.go b/cmd/edgeguard-scheduler/main.go
index d6a5ab8..933667b 100644
--- a/cmd/edgeguard-scheduler/main.go
+++ b/cmd/edgeguard-scheduler/main.go
@@ -41,7 +41,7 @@ import (
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/tlscerts"
 )
 
-var version = "1.1.139"
+var version = "1.1.140"
 
 const (
 	// renewTickInterval — how often we re-evaluate expiring certs.
diff --git a/management-ui/src/i18n/locales/de/common.json b/management-ui/src/i18n/locales/de/common.json
index 3bf035c..0514a9a 100644
--- a/management-ui/src/i18n/locales/de/common.json
+++ b/management-ui/src/i18n/locales/de/common.json
@@ -394,6 +394,7 @@
       "edit": "Server bearbeiten",
       "name": "Server-Name",
       "address": "Adresse",
+      "addressInvalid": "Gültige IPv4/IPv6-Adresse oder Hostname eingeben",
       "port": "Port",
       "target": "Endpoint",
       "weight": "Gewicht",
diff --git a/management-ui/src/i18n/locales/en/common.json b/management-ui/src/i18n/locales/en/common.json
index 57bd4c0..ae51209 100644
--- a/management-ui/src/i18n/locales/en/common.json
+++ b/management-ui/src/i18n/locales/en/common.json
@@ -394,6 +394,7 @@
       "edit": "Edit server",
       "name": "Server name",
       "address": "Address",
+      "addressInvalid": "Enter a valid IPv4/IPv6 address or hostname",
       "port": "Port",
       "target": "Endpoint",
       "weight": "Weight",
diff --git a/management-ui/src/pages/Backends/Detail.tsx b/management-ui/src/pages/Backends/Detail.tsx
index 1442c6a..1145a6a 100644
--- a/management-ui/src/pages/Backends/Detail.tsx
+++ b/management-ui/src/pages/Backends/Detail.tsx
@@ -387,7 +387,14 @@ function ServerPanel({ backendID, haproxyStats, isViewer }: { backendID: number;
           <Form.Item label={t('backends.server.name')} name="name" rules={[{ required: true }]}>
             <Input placeholder="vmm-1" />
           </Form.Item>
-          <Form.Item label={t('backends.server.address')} name="address" rules={[{ required: true }]}>
+          <Form.Item
+            label={t('backends.server.address')}
+            name="address"
+            rules={[
+              { required: true },
+              { pattern: /^(\d{1,3}\.){3}\d{1,3}$|^[0-9a-fA-F:]{2,39}$|^[a-zA-Z0-9]([a-zA-Z0-9\-.]{0,61}[a-zA-Z0-9])?$/, message: t('backends.server.addressInvalid') },
+            ]}
+          >
             <Input placeholder="10.0.0.11" />
           </Form.Item>
           <Form.Item label={t('backends.server.port')} name="port" rules={[{ required: true }]}>
diff --git a/management-ui/src/pages/Domains/index.tsx b/management-ui/src/pages/Domains/index.tsx
index d153ad5..edc6d57 100644
--- a/management-ui/src/pages/Domains/index.tsx
+++ b/management-ui/src/pages/Domains/index.tsx
@@ -413,7 +413,14 @@ export default function DomainsPage() {
               { value: 'https', label: 'https' },
             ]} />
           </Form.Item>
-          <Form.Item label={t('domains.quickBackendAddress')} name="address" rules={[{ required: true }]}>
+          <Form.Item
+            label={t('domains.quickBackendAddress')}
+            name="address"
+            rules={[
+              { required: true },
+              { pattern: /^(\d{1,3}\.){3}\d{1,3}$|^[0-9a-fA-F:]{2,39}$|^[a-zA-Z0-9]([a-zA-Z0-9\-.]{0,61}[a-zA-Z0-9])?$/, message: t('backends.server.addressInvalid') },
+            ]}
+          >
             <Input placeholder="10.0.0.10" />
           </Form.Item>
           <Form.Item label={t('domains.quickBackendPort')} name="port" rules={[{ required: true, type: 'number', min: 1, max: 65535 }]}>