CVE-2026-69088: Grav: Incomplete callable validation in blueprint dynamic fields allows arbitrary static method invocation and file disclosure

Grav CMS’s blueprint dynamic-field callable guard can be bypassed with a fully-qualified Class::method string, letting an account with only page-editing rights (admin.pages, not super-admin) plant a directive in a page’s form-field frontmatter that invokes an arbitrary public static PHP method with attacker-controlled arguments. Using built-in gadget methods this yields, at minimum, arbitrary reading of any server-readable file (disclosed to anonymous visitors of the crafted page) and arbitrary creation/copying of files and directories under the web-server account.