Frappe is a full-stack web application framework. Prior to 15.108.0 and 16.18.3, temporary magic login link generation can use an attacker-controlled request Host header, allowing a remote attacker to cause emailed login links to point to an attacker-controlled domain and capture the login token when a recipient follows the link. This issue is fixed in versions 15.108.0 and 16.18.3.
https://github.com/frappe/frappe/security/advisories/GHSA-3w78-3cj3-p949