The Grav API plugin (getgrav/grav-plugin-api) before 1.0.0-rc.16 shipped Access-Control-Allow-Origin: * as its default CORS configuration on

The Grav API plugin (getgrav/grav-plugin-api) before 1.0.0-rc.16 shipped Access-Control-Allow-Origin: * as its default CORS configuration on all responses, including authenticated endpoints and preflight (OPTIONS) responses. Because the plugin accepts credentials via the Authorization and X-API-Token headers (set programmatically by JavaScript rather than via cookies), an attacker who obtains a valid access token (e.g., via log leakage, Referer headers, browser history, or network capture) can issue fully authenticated cross-origin requests from any malicious website to read sensitive data and perform write operations as the token's user. Fixed in 1.0.0-rc.16.