Authorization Bypass in Grav Flex Objects Plugin

Grav Flex Objects plugin versions 1.4.0 through 1.4.7 are susceptible to an authorization bypass vulnerability (CVE-2026-56707) due to inadequate access control checks within the flex-objects shortcode functionality. The vulnerability enables an authenticated user who possesses basic page-edit access to invoke and render registered Flex collections that should otherwise be restricted by the administrative Access Control List (ACL). By embedding these shortcodes into published pages, an attacker can force the application to disclose sensitive directory contents, including internal user account metadata. This flaw essentially circumvents the intended security posture of the CMS admin panel, allowing for unauthorized data exposure by leveraging legitimate administrative shortcode features against the system.

Attack Chain

1. Attacker gains or authenticates as a user with page-editing privileges within the Grav CMS environment.
2. Attacker identifies the target Flex collection identifiers through reconnaissance of the site structure or documentation.
3. Attacker crafts a malicious page containing the vulnerable flex-objects shortcode targeting the restricted collection.
4. Attacker publishes or saves the page, triggering the server-side rendering of the specified collection.
5. The plugin fails to perform an authorization check on the rendering request against the user's current session permissions.
6. The application processes the shortcode and populates the page with the contents of the sensitive Flex collection.
7. Attacker views the rendered page to scrape or exfiltrate the returned sensitive user data or system information.

Impact

Successful exploitation allows for the unauthorized disclosure of sensitive system data and user account information. Given the nature of the information stored in Flex collections (often utilized for core configuration or user management), this could lead to a significant privacy breach or facilitate further lateral movement or privilege escalation within the Grav CMS environment.

Recommendation

Prioritize the immediate update of the Grav Flex Objects plugin to version 1.4.8 or later to remediate CVE-2026-56707. Audit existing CMS pages for the inclusion of flex-objects shortcodes to identify unauthorized data collection points. Review access logs for webserver requests (cs-uri-stem) associated with page-edit actions followed by excessive data retrieval from Flex collection endpoints.