Claris FileMaker Server before version 20.3.2 was susceptible to a reflected Cross-Site Scripting vulnerability due to an improperly handled parameter in the FileMaker WebDirect login endpoint. The vulnerability was resolved in FileMaker Server 20.3.2 by escaping the HTML contents of the login error message on the login page.
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')