CVE-2026-23921: Blind, read-only SQL injection in Zabbix API via sortfield parameter

A low privilege Zabbix user with API access can exploit a blind SQL injection vulnerability in include/classes/api/CApiService.php to execute arbitrary SQL selects via the sortfield parameter. Although query results are not returned directly, an attacker can exfiltrate arbitrary database data through time-based techniques, potentially leading to session identifier disclosure and administrator account compromise.