# WCK <= 2.3.9 - Reflected Cross-Site Scripting via Upload Field

- **ID:** WPSEC-2026-2388
- **Plugin:** Custom Post Types and Custom Fields creator – WCK (`wck-custom-fields-and-custom-post-types-creator`), https://wordpress.org/plugins/wck-custom-fields-and-custom-post-types-creator/
- **Affected versions:** all versions before 2.4.0
- **Fixed in:** 2.4.0 (Update to 2.4.0 or later.)
- **Severity:** Medium 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-79
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-11-03)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/wck-custom-fields-and-custom-post-types-creator
- **Fix released:** 2026-11-02
- **Published:** 2026-11-03
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2388/

## Description

The WCK plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'postedvalues' parameter rendered in the upload field in all versions up to, and including, 2.3.9. This is due to insufficient input sanitization and output escaping: the value decoded from the parameter is echoed without escaping into the upload field's hidden input value attribute and its data-attachment_id attribute. This makes it possible for unauthenticated attackers to inject arbitrary web scripts into pages that execute if they can successfully trick a user into performing an action such as clicking on a link.

## References

- https://wpsec.com/vuln/WPSEC-2026-2388/
- https://plugins.svn.wordpress.org/wck-custom-fields-and-custom-post-types-creator/tags/2.4.0/
- https://wordpress.org/plugins/wck-custom-fields-and-custom-post-types-creator/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2388/

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.