diff --git a/CHANGELOG b/CHANGELOG
index 39b7991b4..bfaf6b0d5 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix XSS vulnerability in UI messages (#1488030)
 - Fix handling of email addresses with quoted local part (#1487939)
 - Fix EOL character in vCard exports (#1487873)
 - Added optional "multithreading" autocomplete feature
diff --git a/program/include/rcube_json_output.php b/program/include/rcube_json_output.php
index 40a7b2a5e..ade9cc033 100644
--- a/program/include/rcube_json_output.php
+++ b/program/include/rcube_json_output.php
@@ -174,8 +174,15 @@ class rcube_json_output
     public function show_message($message, $type='notice', $vars=null, $override=true, $timeout=0)
     {
         if ($override || !$this->message) {
+            if (rcube_label_exists($message)) {
+                if (!empty($vars))
+                    $vars = array_map('Q', $vars);
+                $msgtext = rcube_label(array('name' => $message, 'vars' => $vars));
+            }
+            else
+                $msgtext = $message;
+
             $this->message = $message;
-            $msgtext = rcube_label_exists($message) ? rcube_label(array('name' => $message, 'vars' => $vars)) : $message;
             $this->command('display_message', $msgtext, $type, $timeout * 1000);
         }
     }
diff --git a/program/include/rcube_template.php b/program/include/rcube_template.php
index 6228e7659..b9a43d3f1 100755
--- a/program/include/rcube_template.php
+++ b/program/include/rcube_template.php
@@ -248,8 +248,15 @@ class rcube_template extends rcube_html_page
     public function show_message($message, $type='notice', $vars=null, $override=true, $timeout=0)
     {
         if ($override || !$this->message) {
+            if (rcube_label_exists($message)) {
+                if (!empty($vars))
+                    $vars = array_map('Q', $vars);
+                $msgtext = rcube_label(array('name' => $message, 'vars' => $vars));
+            }
+            else
+                $msgtext = $message;
+
             $this->message = $message;
-            $msgtext = rcube_label_exists($message) ? rcube_label(array('name' => $message, 'vars' => $vars)) : $message;
             $this->command('display_message', $msgtext, $type, $timeout * 1000);
         }
     }