FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.224, the public endpoint "POST /user-setup/{hash}/{invite_sent_at}" ("OpenController@userSetupSave") selects the target account solely by its "invite_hash" column, then overwrites that account's email and password and logs in as it. No authentication, cookie, or prior session is required. After a user activates, FreeScout sets "invite_hash" to the empty string. On MySQL and MariaDB, "VARCHAR" equality ignores trailing spaces, so a single URL-encoded space ("%20") matches the stored empty string and selects the lowest-id activated user. The expiry guard decrypts "invite_sent_at" with the target's password hash, but "Helper::decrypt" returns its raw input unchanged when decryption fails. A plaintext numeric value such as "9999999999" therefore passes the time-to-live check without any secret. The result is that an anonymous attacker sets the email and password of the lowest-id activated FreeScout account (a support agent, or an administrator if one was added by invitation) and authenticates as that account. Version 1.8.224 contains a fix.