Shield is an authentication and authorization framework for CodeIgniter 4. This vulnerability may allow "SameSite Attackers" (https://canitakeyoursubdomain.name/) to bypass the "CodeIgniter4 CSRF protection" (https://codeigniter4.github.io/userguide/libraries/security.html) mechanism with CodeIgniter Shield. For this attack to succeed, the attacker must have direct (or indirect, e.g., XSS) control over a subdomain site (e.g., "https://a.example.com/") of the target site (e.g., "http://example.com/"). Upgrade to CodeIgniter v4.2.3 or later and Shield v1.0.0-beta.2 or later. As a workaround: set "Config\Security::$csrfProtection" to "'session,'"remove old session data right after login (immediately after ID and password match) and regenerate CSRF token right after login (immediately after ID and password match)