Deserialization of Untrusted Data vulnerability in MainWP MainWP Child mainwp-child allows Object Injection.This issue affects MainWP Child: from n/a through 6.2.1.

The MainWP Child WordPress plugin before 6.1.2 does not verify the requester's identity in its site-registration request handler when password authentication has been disabled for the targeted account, allowing an unauthenticated attacker to obtain a valid authentication session as that account, including an administrator, by naming its login in a single registration request.

The MainWP Child – Securely Connects to the MainWP Dashboard to Manage Multiple Sites plugin for WordPress is vulnerable to privilege escalation due to a missing authorization checks on the registersite function in all versions up to, and including, 5.2 when a site is left in an unconfigured state. This makes it possible for unauthenticated attackers to log in as an administrator on instances where MainWP Child is not yet connected to the MainWP Dashboard. IMPORTANT: this only affects sites who have MainWP Child installed and have not yet connected to the MainWP Dashboard, and do not have the unique security ID feature enabled. Sites already connected to the MainWP Dashboard plugin and do not have the unique security ID feature enabled, are NOT affected and not required to upgrade. Please note versions up to 5.3.3 contained a patch, though a bypass was discovered and not addressed until version 5.3.4.