Fortinet has disclosed CVE-2026-104286, a critical FortiMail vulnerability currently being exploited in the wild. The vulnerability has a CVSS score of 9.8 and can allow an unauthenticated remote attacker to write arbitrary files through crafted HTTP/HTTPS requests. The issue involves path traversal combined with improper NULL-byte handling. For affected deployments, the immediate mitigation includes disabling IBE and restricting access to the FortiMail management interface. Administrators should also investigate their appliances for the published IOCs and preserve evidence if compromise is suspected.