What’s Vulnerable › Vulnerabilities

CVE-2026-4121: Kcaptcha <= 1.0.1 - Cross-Site Request Forgery to Settings Update

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-22 · updated 2026-06-17
• Weakness: CWE-352

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 products

• ksolves Kcaptcha: through 1.0.1

References

• https://plugins.trac.wordpress.org/browser/kcaptcha/tags/1.0.1/admin/setting.php#L12
• https://plugins.trac.wordpress.org/browser/kcaptcha/tags/1.0.1/admin/setting.php#L30
• https://plugins.trac.wordpress.org/browser/kcaptcha/tags/1.0.1/admin/setting.php#L47
• https://plugins.trac.wordpress.org/browser/kcaptcha/trunk/admin/setting.php#L12
• https://plugins.trac.wordpress.org/browser/kcaptcha/trunk/admin/setting.php#L30
• https://plugins.trac.wordpress.org/browser/kcaptcha/trunk/admin/setting.php#L47
• https://www.wordfence.com/threat-intel/vulnerabilities/id/a6c1c73b-76e3-4cb9-ad53-9d5d4e7519c9?source=cve

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