The password reset component deployed within Umbraco uses the hostname supplied within the request host header when building a password reset URL. It may be possible to manipulate the URL sent to Umbraco users when so that it points to the attackers server thereby disclosing the password reset token if/when the link is followed. A related vulnerability (CVE-2022-22690) could allow this flaw to become persistent so that all password reset URLs are affected persistently following a successful attack. See the AppCheck advisory for further information and associated caveats.

Within the Umbraco CMS, a configuration element named "UmbracoApplicationUrl" (or just "ApplicationUrl") is used whenever application code needs to build a URL pointing back to the site. For example, when a user resets their password and the application builds a password reset URL or when the administrator invites users to the site. For Umbraco versions less than 9.2.0, if the Application URL is not specifically configured, the attacker can manipulate this value and store it persistently affecting all users for components where the "UmbracoApplicationUrl" is used. For example, the attacker is able to change the URL users receive when resetting their password so that it points to the attackers server, when the user follows this link the reset token can be intercepted by the attacker resulting in account takeover.