Grav API plugin before v1.0.0-rc.16 accepts JWT tokens via the ?token= URL query parameter and responds with Access-Control-Allow-Origin: *, allowing unauthenticated attackers to make fully authenticated cross-origin API requests from any malicious website. Attackers who obtain a leaked JWT token from access logs, proxy logs, browser history, or Referrer headers can create persistent backdoor super-admin accounts and exfiltrate sensitive configuration and user data.