The traverseStrictSanitize function in admin_dir/includes/classes/AdminRequestSanitizer.php in ZenCart 1.5.5e mishandles key strings, which allows remote authenticated users to execute arbitrary PHP code by placing that code into an invalid array index of the admin_name array parameter to admin_dir/login.php, if there is an export of an error-log entry for that invalid array index.
Cross-site scripting (XSS) vulnerability in zc_install/includes/modules/pages/database_setup/header_php.php in Zen Cart 1.5.0 and earlier, when the software is being installed, allows remote attackers to inject arbitrary web script or HTML via the db_username parameter to zc_install/index.php.
extras/ipn_test_return.php in Zen Cart allows remote attackers to obtain sensitive information via a direct request, which reveals the installation path in an error message.
The installation for Zen Cart stores sensitive information and insecure programs under the (1) docs, (2) extras, and (3) zc_install folders, and (4) install.txt, which allows remote attackers to obtain sensitive information, delete the database, and conduct other attacks via a direct request, different vulnerabilities than CVE-2009-4321 and CVE-2009-4322.