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 strreplace() 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.