The Account Switcher plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.0.2. This is due to the rememberLogin REST API endpoint using a loose comparison (!= instead of !==) for secret validation at app/RestAPI.php:111, combined with no validation that the secret is non-empty. When a target user has never used the "Remember me" feature, their asSecret user meta does not exist, causing get_user_meta() to return an empty string.

An attacker can send an empty secret parameter, which passes the comparison ('' != '' is false), and the endpoint then calls wp_set_auth_cookie() for the target user. Additionally, all REST routes use permission_callback => '__return_true' with no capability checks. This makes it possible for authenticated attackers, with Subscriber-level access and above, to switch to any user account including Administrator, ultimately granting themselves full administrative privileges.