Simple User Registration <= 6.9 - Unauthenticated Privilege Escalation to Administrator

Summary

The MemberHero WordPress plugin through 6.9 does not restrict which account fields can be supplied during its frontend registration process, allowing unauthenticated attackers to register a new user with an arbitrary role, including Administrator, leading to a full site takeover. Version 6.9 is advertised as resolving this issue, but the fix is incomplete and the current version remains exploitable by unauthenticated attackers to obtain administrator access and to take over existing accounts. No version that fully addresses the issue is available at the time of this advisory. Mitigation: deactivate and remove the MemberHero WordPress plugin through 6.9 until a version that fully resolves this issue is released. If the MemberHero WordPress plugin through 6.9 must stay active, disable public registration, restrict access to the registration functionality, and monitor the site for unexpected administrator accounts.