CVE-2026-104286
Fortinet FortiMail Path Traversal Vulnerability
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 due Oct 4, 2026
- Fortinet FortiMail
- Critical
- CVSS 9.8
- EPSS 2.2%
- No fixed version listed
What to do
No fixed version listed
- Required action
- 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.
- CISA deadline for US federal agencies
- Oct 4, 2026
Affected products
| Product | Affected | Fixed in |
|---|---|---|
| Fortinet FortiMail | 8.0.0; from 7.6.0 through 7.6.5; from 7.4.0 through 7.4.6; from 7.2.0 through 7.2.9; from 7.0.0 through 7.0.9 | None listed |
Scores and signals
- Exploitation
- Exploited in the wild
- Severity
- Critical, CVSS 9.8 (v3.1, scored by fortinet)
- EPSS
- 2.2% chance of exploitation in the next 30 days (EPSS from FIRST, as of Oct 23, 2026)
- CISA's SSVC decision points
- Exploitation: active. Automatable: yes. Technical impact: total. As of Oct 2, 2026.
- Weakness
- CWE-22: Execute unauthorized code or commands
- Vendor
- Fortinet, FortiMail
Timeline
- Added to CISA's Known Exploited Vulnerabilities catalog: exploited in the wild. US federal agencies must remediate by 2026-10-04.