The Sunshine Photo Cart: Free Client Photo Galleries for Photographers plugin for WordPress is vulnerable to privilege escalation via account takeover in all versions up to, and including, 3.4.11. This is due to the plugin not properly validating a user-supplied key. This makes it possible for authenticated attackers, with Subscriber-level access and above, to change arbitrary users passwords through the password reset functionality, including administrators, and leverage that to reset the users password and gain access to their account.
When setting a new password for a user, the product does not require knowledge of the original password, or using another form of authentication.