Fortinet warns of critical FortiMail flaw exploited in zero-day attacks

Fortinet has issued a warning about a critical vulnerability in FortiMail, tracked as CVE-2026-104286, which is being actively exploited in zero-day attacks. The flaw allows attackers to execute unauthorized code or commands on vulnerable devices. Fortinet customers are urged to apply mitigations or patches immediately. The exploitation in the wild classifies this as a high-severity, actively exploited vulnerability. Zero-day exploitation indicates that attacks may have begun before a patch was available. FortiMail is widely used in enterprise environments for email security, increasing the potential impact. Organizations using FortiMail should prioritize remediation to prevent unauthorized access or code execution.