Index: phpMyAdmin-4.7.8-all-languages/libraries/common.inc.php
===================================================================
--- phpMyAdmin-4.7.8-all-languages/libraries/common.inc.php
+++ phpMyAdmin-4.7.8-all-languages/libraries/common.inc.php	2019-06-05 00:05:19.570527477 +0200
@@ -682,8 +682,8 @@
                 . ' ' . $cfg['Server']['auth_type']
             );
         }
-        if (isset($_REQUEST['pma_password']) && strlen($_REQUEST['pma_password']) > 256) {
-            $_REQUEST['pma_password'] = substr($_REQUEST['pma_password'], 0, 256);
+        if (isset($_POST['pma_password']) && strlen($_POST['pma_password']) > 256) {
+            $_POST['pma_password'] = substr($_POST['pma_password'], 0, 256);
         }
         $fqnAuthClass = 'PMA\libraries\plugins\auth\\' . $auth_class;
         // todo: add plugin manager
Index: phpMyAdmin-4.7.8-all-languages/libraries/plugins/auth/AuthenticationCookie.php
===================================================================
--- phpMyAdmin-4.7.8-all-languages/libraries/plugins/auth/AuthenticationCookie.php
+++ phpMyAdmin-4.7.8-all-languages/libraries/plugins/auth/AuthenticationCookie.php	2019-06-05 00:04:04.667085950 +0200
@@ -308,7 +308,7 @@
         $GLOBALS['PHP_AUTH_USER'] = $GLOBALS['PHP_AUTH_PW'] = '';
         $GLOBALS['from_cookie'] = false;
 
-        if (isset($_REQUEST['pma_username']) && strlen($_REQUEST['pma_username']) > 0) {
+        if (isset($_POST['pma_username']) && strlen($_POST['pma_username']) > 0) {
 
             // Verify Captcha if it is required.
             if (! empty($GLOBALS['cfg']['CaptchaLoginPrivateKey'])
@@ -350,8 +350,8 @@
             }
 
             // The user just logged in
-            $GLOBALS['PHP_AUTH_USER'] = PMA_sanitizeMySQLUser($_REQUEST['pma_username']);
-            $GLOBALS['PHP_AUTH_PW'] = isset($_REQUEST['pma_password']) ? $_REQUEST['pma_password'] : '';
+            $GLOBALS['PHP_AUTH_USER'] = PMA_sanitizeMySQLUser($_POST['pma_username']);
+            $GLOBALS['PHP_AUTH_PW'] = isset($_POST['pma_password']) ? $_POST['pma_password'] : '';
             if ($GLOBALS['cfg']['AllowArbitraryServer']
                 && isset($_REQUEST['pma_servername'])
             ) {