CVE-2026-16779 in Kubio AI Page Builder Plugin
Summary
by MITRE • 08/16/2026
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.
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Analysis
by VulDB Data Team • 08/16/2026
The vulnerability in the Kubio AI Page Builder plugin for WordPress represents a critical authorization bypass flaw that undermines the security model of the platform. This issue affects all versions up to and including 2.8.5, creating a persistent risk for WordPress installations that utilize this popular page builder tool. The core problem stems from the plugin's failure to implement proper access control verification mechanisms, allowing authenticated users with contributor-level privileges and above to execute unauthorized administrative actions within the WordPress environment.
The technical flaw manifests through the improper handling of authorization checks within the plugin's codebase. While the plugin does implement a nonce validation mechanism using check_ajax_referer(), this protection is fundamentally compromised by the unconditional emission of the nonce value into the window.kubioUtilsData JavaScript object. This design decision exposes the security token to all users who can access the block editor, effectively nullifying the nonce's protective function since any contributor-level user can harvest the token and leverage it for malicious activities.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with substantial control over critical website configuration elements. Authenticated attackers can manipulate front-page configuration options including show_on_front, page_on_front, and page_for_posts parameters, potentially redirecting visitors to malicious content or disrupting the site's primary navigation structure. Additionally, the ability to rewrite primary navigation menu items allows for sophisticated social engineering attacks where legitimate users are redirected to phishing pages or compromised sites.
The vulnerability also enables attackers to replace template parts within the website's design framework, potentially introducing malicious code into the site's frontend components. Furthermore, the capability to overwrite the Kubio global-data post provides access to critical site configuration data that could be leveraged for more extensive attacks including data exfiltration or the establishment of persistent backdoors within the WordPress installation.
This vulnerability aligns with CWE-863, which addresses "Incorrect Authorization" in software systems, and demonstrates how improper access control implementation can create significant security risks even within authenticated environments. From an attack perspective, this issue maps to multiple ATT&CK techniques including privilege escalation through unauthorized modification of system settings and persistence mechanisms through configuration changes that maintain attacker control over the affected WordPress installation.
Organizations should immediately implement mitigations focusing on plugin version updates to the latest secure release, which should contain proper authorization checks and nonce protection mechanisms. Additionally, administrators should review user permissions and consider implementing additional security measures such as role-based access controls that limit contributor-level users' ability to modify core site configuration elements. Regular security auditing of WordPress plugins and themes remains essential for identifying similar authorization bypass vulnerabilities that could compromise the overall security posture of web applications. The incident underscores the critical importance of proper nonce implementation and conditional access control verification in maintaining secure web application environments.