In userman 13.0.76.43 through 15.0.20 in Sangoma FreePBX, XSS exists in the user management screen of the Administrator web site, i.e., the/admin/config.php?display=userman URI. An attacker with sufficient privileges can edit the Display Name of a user and embed malicious XSS code. When another user (such as an admin) visits the main User Management screen, the XSS payload will render and execute in the context of the victim user's account.