Fortinet FortiMail Path Traversal Vulnerability (CVE-2026-104286)
Severity: critical · Patch status: unknown · Since 2026-10-01 · CVE-2026-104286
Fortinet FortiMail contains a path traversal and an improper neutralization of NULL byte or NULL character vulnerability that may allow an unauthenticated attacker to write arbitrary files on the underlying system via crafted HTTP or HTTPS requests. CISA added CVE-2026-104286 to its Known Exploited Vulnerabilities catalog on Oct 1, 2026, which means attackers are exploiting it in the wild.
What to do
- Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- US federal agencies must remediate by Oct 4, 2026 (BOD 22-01); treat that as the outer limit.
Sources
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