The RegistrationMagic WordPress plugin made it possible for unauthenticated users to log in as any site user, including administrators, if they knew a valid username on the site due to missing identity validation in the social login function social_login_using_email() of the plugin. This affects versions equal to, and less than, 5.0.1.7.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-4073
• https://plugins.trac.wordpress.org/changeset/2635173/custom-registration-form-builder-with-submission-manager/trunk/services/class_rm_user_services.php
• https://www.wordfence.com/blog/2021/12/authentication-bypass-vulnerability-patched-in-user-registration-plugin/
• https://www.wordfence.com/vulnerability-advisories/#CVE-2021-4073