Kcaptcha, CVE-2026-4121

CVE, Research URL: CVE-2026-4121
Home page URL: Security reports for Kcaptcha
Application: Kcaptcha
Published on: Apr 22, 2026
Research Description: The Kcaptcha plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to and including 1.0.1. This is due to missing nonce validation in the plugin's settings page handler (admin/setting.php). The settings form does not include a wp_nonce_field() and the form processing code does not call wp_verify_nonce() or check_admin_referer() before saving settings to the database via $wpdb->update(). This makes it possible for unauthenticated attackers to modify the plugin's CAPTCHA settings (enabling or disabling CAPTCHA on login, registration, lost password, and comment forms) via a forged request, granted they can trick a site administrator into performing an action such as clicking a link.
Affected versions: max 1.0.1.
Status: vulnerable