A Zabbix user with API access can exploit a blind SQL injection in the `CApiService.php` file. The issue resides in the `sortfield` parameter, allowing an attacker to execute arbitrary SQL selects. While query results are not directly returned, data can be exfiltrated using time-based techniques. This could lead to the disclosure of session identifiers and compromise of administrator accounts. The vulnerable component is located at the API endpoint include/classes/api/`CApiService.php`. The vulnerable parameter is `sortfield`.