# MailChimp Forms by MailMunch <= 3.2.9 - Cross-Site Request Forgery to MailMunch Account Unlinking

- **ID:** WPSEC-2026-0830
- **Plugin:** Mailmunch Forms for Mailchimp (`mailchimp-forms-by-mailmunch`), https://wordpress.org/plugins/mailchimp-forms-by-mailmunch/
- **Affected versions:** all versions before 3.3.0
- **Fixed in:** 3.3.0 (Update to 3.3.0 or later.)
- **Severity:** Medium 4.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N)
- **Weakness:** CWE-352
- **Usage among sites WPSec scans:** plugin Low, affected versions None seen (as of 2026-10-13)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/mailchimp-forms-by-mailmunch
- **Fix released:** 2026-10-12
- **Published:** 2026-10-13
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0830/

## Description

The Mailmunch Forms for Mailchimp plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.2.9. This is due to missing nonce validation and a missing capability check on the 'sign_out' step of the plugin's admin page handler. This makes it possible for unauthenticated attackers to unlink the site's connected MailMunch account through a forged request, provided they can trick a logged-in site administrator into performing an action such as clicking a link.

## References

- https://wpsec.com/vuln/WPSEC-2026-0830/
- https://plugins.svn.wordpress.org/mailchimp-forms-by-mailmunch/tags/3.3.0/
- https://wordpress.org/plugins/mailchimp-forms-by-mailmunch/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0830/

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.