diff --git a/CHANGELOG b/CHANGELOG
index 6456fa678..c6ac453ab 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -9,6 +9,7 @@ CHANGELOG Roundcube Webmail
 - PGP encryption support via Mailvelope integration
 - PGP encryption support via Enigma plugin
 - PHP7 compatibility fixes (#1490416)
+- Security: Added options to validate username/password on logon (#1490500)
 - Security: Improve randomness of security tokens (#1490529)
 - Security: Use random security tokens instead of hashes based on encryption key (#1490404)
 - Security: Improved encrypt/decrypt methods with option to choose the cipher_method (#1489719)
diff --git a/config/defaults.inc.php b/config/defaults.inc.php
index d53b70007..eef7de47f 100644
--- a/config/defaults.inc.php
+++ b/config/defaults.inc.php
@@ -306,6 +306,7 @@ $config['ldap_cache'] = 'db';
 // Lifetime of LDAP cache. Possible units: s, m, h, d, w
 $config['ldap_cache_ttl'] = '10m';
 
+
 // ----------------------------------
 // SYSTEM
 // ----------------------------------
@@ -377,6 +378,14 @@ $config['login_autocomplete'] = 0;
 //       UPDATE users SET username = LOWER(username);
 $config['login_lc'] = 2;
 
+// Maximum length (in bytes) of logon username and password.
+$config['login_username_maxlen'] = 1024;
+$config['login_password_maxlen'] = 1024;
+
+// Logon username filter. Regular expression for use with preg_match().
+// Example: '/^[a-z0-9_@.-]+$/'
+$config['login_username_filter'] = null;
+
 // Includes should be interpreted as PHP files
 $config['skin_include_php'] = false;
 
diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index 81a1c817c..d74b70534 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -493,7 +493,7 @@ class rcmail extends rcube
      *
      * @return boolean True on success, False on failure
      */
-    function login($username, $pass, $host = null, $cookiecheck = false)
+    function login($username, $password, $host = null, $cookiecheck = false)
     {
         $this->login_error = null;
 
@@ -506,11 +506,23 @@ class rcmail extends rcube
             return false;
         }
 
+        $username_filter = $this->config->get('login_username_filter');
+        $username_maxlen = $this->config->get('login_username_maxlen', 1024);
+        $password_maxlen = $this->config->get('login_password_maxlen', 1024);
         $default_host    = $this->config->get('default_host');
         $default_port    = $this->config->get('default_port');
         $username_domain = $this->config->get('username_domain');
         $login_lc        = $this->config->get('login_lc', 2);
 
+        // check input for security (#1490500)
+        if (($username_maxlen && strlen($username) > $username_maxlen)
+            || ($username_filter && !preg_match($username_filter, $username))
+            || ($password_maxlen && strlen($password) > $password_maxlen)
+        ) {
+            $this->login_error = self::ERROR_INVALID_REQUEST;
+            return false;
+        }
+
         // host is validated in rcmail::autoselect_host(), so here
         // we'll only handle unset host (if possible)
         if (!$host && !empty($default_host)) {
@@ -595,7 +607,7 @@ class rcmail extends rcube
         $storage = $this->get_storage();
 
         // try to log in
-        if (!$storage->connect($host, $username, $pass, $port, $ssl)) {
+        if (!$storage->connect($host, $username, $password, $port, $ssl)) {
             // Wait a second to slow down brute-force attacks (#1490549)
             sleep(1);
             return false;
@@ -643,7 +655,7 @@ class rcmail extends rcube
             $_SESSION['storage_host'] = $host;
             $_SESSION['storage_port'] = $port;
             $_SESSION['storage_ssl']  = $ssl;
-            $_SESSION['password']     = $this->encrypt($pass);
+            $_SESSION['password']     = $this->encrypt($password);
             $_SESSION['login_time']   = time();
 
             if (isset($_REQUEST['_timezone']) && $_REQUEST['_timezone'] != '_default_') {
@@ -1069,6 +1081,12 @@ class rcmail extends rcube
 
         // failed login
         if ($failed_login) {
+            // don't fill the log with complete input, which could
+            // have been prepared by a hacker
+            if (strlen($user) > 256) {
+                $user = substr($user, 0, 256) . '...';
+            }
+
             $message = sprintf('Failed login for %s from %s in session %s (error: %d)',
                 $user, rcube_utils::remote_ip(), session_id(), $error_code);
         }