hCaptcha for WP <= 5.4.1 - Unauthenticated CAPTCHA Bypass via MailPoet Subscription Requests
- ID
- WPSEC-2026-2313
- Plugin
- hCaptcha for WP (hcaptcha-for-forms-and-more)
- Affected
- all versions before 5.5.0
- Remediation
- Update to 5.5.0 or later.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Weakness
- CWE-693
- Usage
- Plugin Medium · Affected versions Medium among sites WPSec scans, 2026-11-03
- Attack surface
- hCaptcha for WP on WPSec AttackSurface
- Fix released
- Published
Description
The hCaptcha for WP plugin for WordPress is vulnerable to a protection mechanism bypass via the MailPoet integration in all versions up to, and including, 5.4.1. This is due to the subscription check matching only the exact POST values action=mailpoet, endpoint=subscribers and method=subscribe, while MailPoet dispatches on the request action, trims and normalizes the endpoint and method names, and accepts the 'mailpoet_method' alias, and to MailPoet's admin-post subscription handler (mailpoet_subscription_form) not being checked at all. This makes it possible for unauthenticated attackers to subscribe addresses to MailPoet lists without solving the hCaptcha challenge.
References
- https://wpsec.com/vuln/WPSEC-2026-2313/
- https://plugins.svn.wordpress.org/hcaptcha-for-forms-and-more/tags/5.5.0/
- https://wordpress.org/plugins/hcaptcha-for-forms-and-more/
Published by WPSec. Provided as is, without warranty. Corrections: contact us.
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