Fix PHP fatal error when parsing some malformed BODYSTRUCTURE responses (#9689)

CHANGELOG.md

@@ -67,6 +67,7 @@
 - Fix rcube_imap::get_vendor() result (and PHP warning) on Zimbra server (#9650)
 - Fix regression causing inline SVG images to be missing in mail preview (#9644)
 - Fix plugin "virtuser_file" to handle backward slashes in username (#9668)
+- Fix PHP fatal error when parsing some malformed BODYSTRUCTURE responses (#9689)
 
 ## Release 1.6.9
 

program/lib/Roundcube/rcube_imap.php

@@ -2282,7 +2282,7 @@ class rcube_imap extends rcube_storage
     protected function is_attachment_part($part)
     {
         if (!empty($part[2]) && is_array($part[2]) && empty($part[3])) {
-            $params = array_map('strtolower', (array) $part[2]);
+            $params = array_map('strtolower', array_filter($part[2], 'is_string'));
             $find = ['name', 'filename', 'name*', 'filename*', 'name*0', 'filename*0', 'name*0*', 'filename*0*'];
 
             // In case of malformed header check disposition. E.g. some servers for
@@ -2304,7 +2304,7 @@ class rcube_imap extends rcube_storage
     protected function structure_charset($structure)
     {
         while (is_array($structure)) {
-            if (is_array($structure[2]) && $structure[2][0] == 'charset') {
+            if (isset($structure[2]) && is_array($structure[2]) && $structure[2][0] == 'charset') {
                 return $structure[2][1];
             }