# Kit (formerly ConvertKit) – Email Subscribers, Email Newsletter, Email Marketing, Landing Pages and Membership <= 3.5.0 - Unauthenticated Sensitive Information Exposure via AJAX Requests

- **ID:** WPSEC-2026-2851
- **Plugin:** Kit (formerly ConvertKit) – Email Subscribers, Email Newsletter, Email Marketing, Landing Pages and Membership (`convertkit`), https://wordpress.org/plugins/convertkit/
- **Affected versions:** from 2.1.0 before 3.5.1
- **Fixed in:** 3.5.1 (Update to 3.5.1 or later.)
- **Severity:** Medium 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
- **Weakness:** CWE-200
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-11-12)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/convertkit
- **Fix released:** 2026-11-10
- **Published:** 2026-11-12
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2851/

## Description

The Kit (formerly ConvertKit) plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 3.5.0. This is due to the Member Content filter not restricting post content that is output during AJAX requests, because the filter is only registered on the 'wp' action, which does not run for AJAX requests. This makes it possible for unauthenticated attackers to read member-only content of restricted pages and posts when a theme or plugin outputs post content over AJAX, for example through a 'load more' button.

## References

- https://wpsec.com/vuln/WPSEC-2026-2851/
- https://plugins.svn.wordpress.org/convertkit/tags/3.5.1/
- https://wordpress.org/plugins/convertkit/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2851/

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.