SugarCRM before 6.1.3 does not properly handle reloads and direct requests for a warning page produced by a certain duplicate check, which allows remote authenticated users to discover (1) the names of customers via a ShowDuplicates action to the Accounts module, reachable through index.php; or (2) the names of contact persons via a ShowDuplicates action to the Contacts module, reachable through index.php.