CVE-2026-4121

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-04-22 09:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 10:56 UTC Last updatedMost recent change to the record

Details

Published

2026-04-22 09:16 UTC

Last modified

2026-06-17 10:56 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-352 · Cross-site request forgery

Record status

Deferred

Attack profile CVSS 3.1 · 4.3

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None