FOG is a free open-source cloning/imaging/rescue suite/inventory management system. Prior to versions 1.5.10.1832 and 1.6.0-beta.2313, the buildRow() method in fogpage.class.php substitutes data values into HTML table cell templates using str_replace() without any HTML escaping. An unauthenticated attacker who knows any registered host's MAC address can POST malicious inventory values (e.g. sysproduct, sysserial) to /service/inventory.php, which stores them in the database. When an administrator opens the Group Inventory tab, the payload renders as executable HTML/JavaScript in the admin's browser. Versions 1.5.10.1832 and 1.6.0-beta.2313 fix the issue.