CVE-2025-8487: Kubio AI Page Builder Auth Bypass Flaw

CVE-2025-8487 Overview

CVE-2025-8487 affects the Kubio AI Page Builder plugin for WordPress in all versions up to and including 2.6.3. The plugin exposes the kubio-image-hub-install-plugin AJAX action without a capability check. Authenticated users with Subscriber-level access or higher can invoke this action to install the Image Hub plugin on the target site. The flaw is classified as Missing Authorization [CWE-862].

Critical Impact
Low-privileged WordPress users can install an additional plugin on the site without administrative approval, expanding the attack surface and enabling follow-on compromise if the installed plugin itself introduces exploitable code.

Affected Products

Kubio AI Page Builder plugin for WordPress
All versions up to and including 2.6.3
WordPress sites permitting Subscriber-level registration are at highest exposure

Discovery Timeline

2025-09-19 - CVE-2025-8487 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-8487

Vulnerability Analysis

The vulnerability resides in the Image Hub integration shipped with Kubio AI Page Builder. The plugin registers an AJAX handler named kubio-image-hub-install-plugin that installs the Image Hub companion plugin. The handler validates that the request originates from an authenticated user but does not verify that the user holds the install_plugins capability normally reserved for administrators. Any account that can log in — including Subscribers created through open registration — can trigger the installation routine.

The consequence is a break in WordPress's role-based access control model. Plugin installation is an administrative action, and delegating it to Subscribers grants them influence over the site's executing codebase. If the Image Hub plugin later develops its own vulnerability, or if attackers chain this issue with other flaws, an attacker gains a durable foothold on the site.

Root Cause

The root cause is a missing capability check in the AJAX callback registered for wp_ajax_kubio-image-hub-install-plugin. The handler relies on authentication alone through the standard wp_ajax_ hook and omits a current_user_can('install_plugins') gate. The upstream fix in changeset 3361499 adds authorization logic to the handler in lib/integrations/image-hub/image-hub.php.

Attack Vector

Exploitation is remote and requires authentication at Subscriber level or above. An attacker registers an account on a site allowing self-registration, obtains a valid session and nonce, then issues a POST request to /wp-admin/admin-ajax.php with action=kubio-image-hub-install-plugin. The server downloads and installs the Image Hub plugin without further authorization. See the WordPress Plugin Code Reference for the vulnerable handler.

Detection Methods for CVE-2025-8487

Indicators of Compromise

Requests to /wp-admin/admin-ajax.php with action=kubio-image-hub-install-plugin originating from non-administrator sessions
Unexpected presence of the Image Hub plugin directory under wp-content/plugins/ on sites that did not intentionally install it
New entries in the WordPress active_plugins option or plugin install logs correlated with Subscriber account activity

Detection Strategies

Monitor WordPress admin-ajax.php traffic for the specific action string and flag invocations by users whose roles lack install_plugins
Enable file integrity monitoring on wp-content/plugins/ to detect unauthorized plugin directories appearing outside of scheduled maintenance windows
Review WordPress audit logs, if a logging plugin is installed, for activated_plugin and installed_plugin events tied to non-administrator user IDs

Monitoring Recommendations

Alert on new user registrations followed by AJAX calls to installer endpoints within a short time window
Track outbound HTTP requests from the WordPress host to downloads.wordpress.org occurring outside change-management windows
Correlate plugin installation events with the originating user role and source IP to surface abuse patterns

How to Mitigate CVE-2025-8487

Immediate Actions Required

Upgrade Kubio AI Page Builder to the version released after 2.6.3 that incorporates changeset 3361499
Audit wp-content/plugins/ for the presence of the Image Hub plugin and remove it if it was installed without authorization
Review recently registered Subscriber accounts and revoke any that appear suspicious or unused

Patch Information

The vendor addressed the issue in the commit tracked as WordPress Plugin Changeset 3361499, which adds the missing capability check to the kubio-image-hub-install-plugin AJAX handler. Refer to the Wordfence Vulnerability Report for advisory details and version guidance.

Workarounds

Disable open user registration in WordPress settings until the plugin is patched
Restrict access to /wp-admin/admin-ajax.php for unauthenticated and low-privileged users at the web application firewall layer
Temporarily deactivate the Kubio AI Page Builder plugin on sites that cannot upgrade immediately

bash

# Configuration example: block the vulnerable AJAX action at the WAF/nginx layer
location = /wp-admin/admin-ajax.php {
    if ($arg_action = "kubio-image-hub-install-plugin") {
        return 403;
    }
}