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.

01What is this 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.

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2026-10-01. Ransomware use: Unknown.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

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07Related CVEs

08Timeline

• Published: —
• Last modified: —
• Added to CISA KEV: 2026-10-01
• BOD 22-01 due: 2026-10-04

09References

No additional references available in the KB record.