# 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`), https://wordpress.org/plugins/hcaptcha-for-forms-and-more/
- **Affected versions:** all versions before 5.5.0
- **Fixed in:** 5.5.0 (Update to 5.5.0 or later.)
- **Severity:** Medium 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)
- **Weakness:** CWE-693
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-11-03)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/hcaptcha-for-forms-and-more
- **Fix released:** 2026-10-30
- **Published:** 2026-11-03
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2313/

## 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/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2313/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.