A cross-site scripting (XSS) vulnerability in LemonLDAP::NG before 2.20.1 allows remote attackers to inject arbitrary web script or HTML via the url parameter of the upgrade session confirmation page (upgradeSession / forceUpgrade) if the "Upgrade session" plugin has been enabled by an admin
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.