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

- **ID:** WPSEC-2026-2853
- **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-2026-2853/

## Description

The Kit (formerly ConvertKit) plugin for WordPress is vulnerable to Sensitive Information Exposure via the REST API in all versions up to, and including, 3.5.0. This is due to the Member Content restriction on REST API responses replacing only the rendered content of restricted posts. It leaves the excerpt that WordPress generates from the post content unchanged, and it skips the restriction entirely when only the excerpt is requested through the _fields parameter. This makes it possible for unauthenticated attackers to read member-only content of restricted pages and posts.

## References

- https://wpsec.com/vuln/WPSEC-2026-2853/
- https://plugins.svn.wordpress.org/convertkit/tags/3.5.1/
- https://wordpress.org/plugins/convertkit/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2853/

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.