The /users endpoint in Statamic Core before 2.11.8 allows XSS to add an administrator user. This can be exploited via CSRF. Stored XSS can occur via a JavaScript payload in a username during account registration. Reflected XSS can occur via the /users PATH_INFO.
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.