Grav Flex Objects - Server-Side Template Injection via Dynamic Titles

The bundled Grav Flex Objects plugin (getgrav/grav-plugin-flex-objects) before 1.4.0 contains a stored server-side template injection vulnerability. When rendering dynamic collection or object titles, the plugin passes user-controlled frontmatter values (page.header.flex.collection.title or page.header.flex.object.title) to Twig's template_from_string(), causing them to be evaluated as Twig code rather than treated as text. This path bypasses Grav's Security::cleanDangerousTwig() sanitization. An attacker who can control the title frontmatter of a publicly reachable Flex Objects page can achieve arbitrary Twig execution and escalate to remote command execution via access to internal Grav services such as the scheduler.