CVE-2026-104286FortinetServers and softwareOctober 1, 2026

Fortinet FortiMail Path Traversal Vulnerability

Critical 9.8Actively exploited

Description

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.

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.

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Details

Vendor
Fortinet
Product
FortiMail
CVE
CVE-2026-104286
Affected versions
FortiMail 8.0: from 8.0.0 to 8.0.1
FortiMail 7.6: from 7.6.0 to 7.6.6
FortiMail 7.4: from 7.4.0 to 7.4.8
FortiMail 7.2: from 7.2.0 to 7.2.9
FortiMail 7.0: from 7.0.0 to 7.0.9 (from the advisory and NVD; check the exact builds in the official advisory)
CVSS score
9.8
Actively exploited
Yes, listed in the CISA Known Exploited Vulnerabilities catalog
CISA due date
October 4, 2026 (deadline for US federal agencies: a good benchmark for you too)
Source
CISA KEV – original advisory
Published
October 1, 2026

The description and the recommended action are quoted from the public advisory; severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.

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