The Grav Admin2 plugin (getgrav/grav-plugin-admin2) before 2.0.4 embeds a global JavaScript variable window.GRAVCONFIG in the Admin2 SPA bootstrap page at /grav/admin (and its subroutes). This object is returned in every unauthenticated response and discloses the server URL, API prefix, admin base path, runtime environment type, and exact Grav and Admin2 version numbers, allowing an unauthenticated attacker to fingerprint the deployment and select version-specific exploits without reconnaissance.

Grav Admin (getgrav/grav-plugin-admin2) versions <= 2.0.19 contain a stored cross-site scripting vulnerability in the tHtml() function (src/lib/stores/i18n.svelte.ts), which substitutes untrusted parameters such as usernames into translation templates before parsing the result as markdown. Grav's server-side username validation (DataUser::isValidUsername) blocks filesystem-dangerous characters but not <, >, ", or ', allowing an attacker to register a username containing an HTML payload. When an administrator views a UI surface that renders the username through tHtml()—such as the two-factor force-disable confirmation prompt or the 'page is locked' editor notice—the payload executes in their authenticated session. Fixed in 2.0.21.