IceWarp Web Mail 5.5.1, as used by Merak Mail Server 8.3.0r and VisNetic Mail Server version 8.3.0 build 1, does not properly restrict acceptable values for the language parameter to mail/settings.html before it is stored in a database, which can allow remote authenticated users to include arbitrary PHP code via a URL in a modified lang_settings parameter to mail/index.html.