Description

The Kubio AI Page Builder plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 2.8.5. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with contributor-level access and above, to overwrite front-page configuration options (show_on_front, page_on_front, and page_for_posts), rewrite primary navigation menu items, replace template parts, and overwrite the Kubio global-data post. Although a nonce check via check_ajax_referer() is present, the nonce is unconditionally emitted into window.kubioUtilsData for every user who can load the block editor, making it harvestable by any Contributor and therefore an ineffective authorization barrier.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.3",
  "pubDate": "2026-08-16T05:16:47.910Z",
  "pubdate": "2026-08-16T05:16:47.910Z",
  "executiveSummary": "The Kubio AI Page Builder plugin for WordPress, in all versions up to and including 2.8.5, suffers from an authorization bypass vulnerability.\nThis security flaw stems from improper access control validation and weak nonce implementation, allowing authenticated users with low privileges, specifically contributor-level access and above, to execute unauthorized administrative actions.\nThe vulnerability impacts WordPress installations utilizing the vulnerable plugin versions, posing significant risks to site integrity and configuration management.\nAn attacker possessing contributor-level privileges can leverage this flaw to overwrite critical front-page configuration options including show_on_front, page_on_front, and page_for_posts, rewrite primary navigation menu items, replace template parts, and overwrite the Kubio global-data post.\nExploitation requires authenticated access at the contributor level and the ability to load the block editor, which exposes the necessary cryptographic nonce.\nThe risk implications include unauthorized modification of core site routing, structural template manipulation, and potential defacement or hijacking of primary site navigation structures.",
  "technicalDetails": "The root cause of the vulnerability is the absence of robust authorization checks within the Kubio AI Page Builder plugin, combined with a flawed implementation of cryptographic nonces.\nAlthough the plugin implements a nonce check via the check_ajax_referer() function, the underlying security mechanism fails because the nonce is unconditionally emitted into the window.kubioUtilsData JavaScript object for any user capable of loading the block editor.\nConsequently, this design flaw makes the nonce harvestable by any authenticated user holding contributor-level access and above.\nThe attack flow begins when an authenticated attacker with contributor privileges logs into the WordPress dashboard and loads the block editor.\nDuring this process, the attacker extracts the exposed nonce from the window.kubioUtilsData global variable.\nThe attacker then crafts and transmits an AJAX request containing the harvested nonce to invoke backend functionality intended for higher-privileged users.\nBecause the plugin trusts the presence of the valid nonce without verifying whether the requesting user actually possesses the appropriate administrative capabilities to perform the requested actions, the backend executes the state-changing operations.\nThrough this payload execution, the attacker can overwrite critical front-page configuration options such as show_on_front, page_on_front, and page_for_posts.\nAdditionally, the attacker can rewrite primary navigation menu items, replace theme template parts, and overwrite the designated Kubio global-data post.\nThe affected component involves the AJAX request handling and authorization verification routines within the Kubio AI Page Builder plugin across all versions up to and including 2.8.5.\nThe vulnerability requires network exposure via the WordPress admin interface, authenticated access, contributor-level privileges, and the capability to load the block editor to harvest the required nonce."
}