# MainWP Child – Securely Connects to the MainWP Dashboard to Manage Multiple Sites <= 6.3 - Missing Authorization to Branding Disconnected State Update via Site Registration

- **ID:** WPSEC-2026-2126
- **Plugin:** MainWP Child – Securely Connects to the MainWP Dashboard to Manage Multiple Sites (`mainwp-child`), https://wordpress.org/plugins/mainwp-child/
- **Affected versions:** all versions before 6.4
- **Fixed in:** 6.4 (Update to 6.4 or later.)
- **Severity:** Medium 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)
- **Weakness:** CWE-862
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-10-30)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/mainwp-child
- **Fix released:** 2026-10-29
- **Published:** 2026-10-30
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2126/

## Description

The MainWP Child plugin for WordPress is vulnerable to unauthorized modification of data via the site registration request in all versions up to, and including, 6.3, due to a missing authorization check in the register_site() function. On a site that is already connected, a registration request for any username that has password authentication enabled, or for a username that does not exist, sets the 'branding_disconnected' option to 'yes' before any credential is checked. This makes it possible for unauthenticated attackers to cancel the site's white-label branding settings (unless 'preserve branding' is enabled), which shows a plugin hidden by branding again and lifts the menu restrictions branding applies.

## References

- https://wpsec.com/vuln/WPSEC-2026-2126/
- https://plugins.svn.wordpress.org/mainwp-child/tags/6.4/
- https://wordpress.org/plugins/mainwp-child/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2126/

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.