CVE-2026-12349 in Premium Addons for KingComposer Plugin
Summary
by MITRE • 06/30/2026
The Premium Addons for KingComposer plugin for WordPress is vulnerable to unauthorized modification and loss of data in versions up to, and including, 1.1.1. This is due to missing authorization and capability checks on the add_custom_sidebar() and remove_custom_sidebar() AJAX handlers, both of which are exposed through wp_ajax_nopriv_* hooks and write directly to the octagon_custom_sidebar option via update_option(). This makes it possible for unauthenticated attackers to create arbitrary custom widget areas or delete existing custom sidebars, which can cause widgets assigned to those areas to silently lose their registration and stop rendering.
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Analysis
by VulDB Data Team • 06/30/2026
The vulnerability in Premium Addons for KingComposer plugin represents a critical authorization flaw that undermines the security posture of WordPress installations. This issue affects versions up to and including 1.1.1 where the plugin fails to implement proper access controls for its administrative functions. The flaw manifests through two specific AJAX handlers add_custom_sidebar() and remove_custom_sidebar() which are improperly exposed through wp_ajax_nopriv_* hooks, eliminating the need for authentication or authorization checks. These handlers directly manipulate the octagon_custom_sidebar option using update_option() function, creating a direct pathway for unauthorized modifications to the site's sidebar configuration.
The technical implementation of this vulnerability stems from improper capability validation within the plugin's AJAX handler registration process. The wp_ajax_nopriv_* hooks are designed to allow unauthenticated access to specific functions, but in this case they have been incorrectly applied to administrative operations that should require proper user authentication and authorization. When attackers exploit this weakness, they can execute arbitrary sidebar modifications without any credentials or privileges, effectively bypassing WordPress's built-in security mechanisms that normally protect such critical configuration elements. The direct use of update_option() function creates an immediate impact on the site's database configuration, allowing attackers to modify core widget area definitions that control content rendering.
The operational impact of this vulnerability extends beyond simple data modification to include potential service disruption and content availability issues. Unauthenticated attackers can create malicious custom widget areas that may contain harmful content or simply delete existing sidebar configurations causing widgets to lose their registration and become non-functional. This silent failure mode is particularly dangerous as it does not generate obvious error messages or alerts, making the compromise difficult to detect until site administrators notice missing or broken content elements. The vulnerability creates a persistent threat where attackers can repeatedly modify sidebar configurations without detection, potentially leading to complete loss of widget functionality and degraded user experience across the affected WordPress installation.
The security implications align with CWE-863 (Incorrect Authorization) and represent a clear violation of the principle of least privilege that should govern all administrative operations within WordPress plugins. This vulnerability maps directly to attack techniques described in MITRE ATT&CK framework under T1059 (Command and Scripting Interpreter) and T1078 (Valid Accounts) where attackers leverage exposed administrative interfaces to gain unauthorized access to system configuration elements. The recommended mitigation strategy involves immediate plugin updates to versions that implement proper capability checks and authorization validation for all AJAX handlers that modify core site configurations. Additionally, administrators should implement network-level restrictions on wp-admin and wp-ajax endpoints, conduct thorough security audits of all installed plugins, and consider implementing Web Application Firewall rules to monitor and block suspicious requests targeting these specific vulnerability vectors.
Organizations should also consider implementing monitoring solutions that track changes to sidebar configurations and widget assignments, as this vulnerability can be exploited repeatedly without leaving obvious traces in standard logs. The patching process must be prioritized immediately, as the vulnerability provides attackers with a persistent method for modifying site configuration. Regular security assessments of plugin installations remain critical for identifying similar authorization flaws in other third-party components that may expose similar attack surfaces through improper hook registration or missing capability validation mechanisms.