# Smart Popup by Supsystic <= 2.0.0 - Unauthenticated Server-Side Request Forgery via getMailchimpGroups AJAX Action

- **ID:** WPSEC-2026-1522
- **Plugin:** Customer Engagement System – Popup Builder, Forms, CRM & Email Marketing Automation (`popup-by-supsystic`), https://wordpress.org/plugins/popup-by-supsystic/
- **Affected versions:** all versions before 2.0.2
- **Fixed in:** 2.0.2 (Update to 2.0.2 or later.)
- **Severity:** High 7.2 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-918
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-10-23)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/popup-by-supsystic
- **Fix released:** 2026-10-22
- **Published:** 2026-10-23
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1522/

## Description

The Popup Builder, Forms, CRM & Email Marketing Automation plugin for WordPress is vulnerable to Server-Side Request Forgery via the getMailchimpGroups AJAX action in all versions up to, and including, 2.0.0. This is due to two gaps: the action has no capability check or nonce verification, and the datacenter part of the MailChimp API key supplied in the request is placed into the API host without validation. This makes it possible for unauthenticated attackers to make web requests to arbitrary locations originating from the web application, which can be used to query and modify information from internal services. The affected code is in the plugin's legacy runtime, which is loaded on sites that used the plugin before the 2.0 release.

## References

- https://wpsec.com/vuln/WPSEC-2026-1522/
- https://plugins.svn.wordpress.org/popup-by-supsystic/tags/2.0.2/
- https://wordpress.org/plugins/popup-by-supsystic/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1522/

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.