CVE-2026-104286 Fortinet FortiMail: file path flaw
In plain words: The program can be tricked into reading or writing files outside the folder it should stay in. Leaks files such as passwords and settings, or overwrites important ones.
Confirmed exploited by CISA on · US federal patch deadline Oct 4, 2026
What to do
- Install Fortinet's security update for FortiMail. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Patch edge devices first — attackers often start scanning for them within hours of a fix.
- Never expose the device's admin page to the internet.
- After patching a device that was exposed, follow the vendor's compromise checks, end active sessions and change passwords.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: They face the internet and guard the whole network, so a flaw here can hand attackers a way in — and these devices usually run no antivirus, so break-ins go unnoticed.
The details
- Official name
- Fortinet FortiMail Path Traversal Vulnerability
- Product
- Fortinet FortiMail
- CISA 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.
- Type of flaw
- File path flaw (CWE-22, CWE-158)
- Confirmed exploited
- Oct 1, 2026
- US federal patch deadline
- Oct 4, 2026
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Answering about CVE-2026-104286 ·
Questions about CVE-2026-104286
Is CVE-2026-104286 being exploited?
Yes. CISA added CVE-2026-104286 to its Known Exploited Vulnerabilities catalog on Oct 1, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2026-104286?
Install Fortinet's security update for FortiMail. If no update exists, follow the vendor's workaround or stop using the product until one ships. Patch edge devices first — attackers often start scanning for them within hours of a fix.
Am I affected by CVE-2026-104286?
Only if you use Fortinet FortiMail. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.