Zen Cart 1.6.0 has XSS in the main_page parameter to index.php. NOTE: 1.6.0 is not an official release but the vendor's README.md file offers a link to v160.zip with a description of "Download latest in-development version from github."
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.