Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-104286

FortiMail Path traversal

Fortinet / FortiMail · 8.0.0

View live feed Monitor via API Watch CVE-2026-104286
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
—
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-104286 is an unauthenticated vulnerability affecting Fortinet FortiMail. An improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiMail 8.0.0 through...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Fortinet / FortiMail 8.0.0.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

FortiMail Path traversal

An improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiMail 8.0.0 through 8.0.1, FortiMail 7.6.0 through 7.6.6, FortiMail 7.4.0 through 7.4.8, FortiMail 7.2.0 through 7.2.9 may allow an unauthenticated attacker to write arbitrary files on the underlying system via crafted HTTP or HTTPS requests.

Fortinet Affected
FortiMail
8.0.0 Through 7.6.5 Through 7.4.6 Through 7.2.9 Through 7.0.9
Published
01 Oct 2026
Exploitation Reported
01 Oct 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

edge cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

FortiGuard Center - Outbreak Alerts

Recorded 01 Oct 2026

A trusted third party reported exploitation.

Proof of concept available

GitHub

Recorded 01 Oct 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
FortiGuard Center - Outbreak Alerts First 2026-10-01 19:38 UTC
FortiGuard 2026-10-01 19:47 UTC
CISA 2026-10-01 20:01 UTC
The Hacker News 2026-10-02 06:21 UTC
Security Affairs 2026-10-02 07:21 UTC
CERT Polska 2026-10-02 09:21 UTC
TheRegister 2026-10-02 11:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C

EPSS

—

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22

Recent mention · TheRegister

Fortinet sounds the alarm over actively exploited FortiMail zero-day

No login required, exploitation underway, and some admins are still waiting for patches

Read full advisory

All Mentions

Recent mention · TheRegister

Fortinet sounds the alarm over actively exploited FortiMail zero-day

TheRegister · 02 Oct 2026

No login required, exploitation underway, and some admins are still waiting for patches

Recent mention · CERT Polska

Krytyczna podatność w FortiMail aktywnie wykorzystywana w atakach

CERT Polska · 02 Oct 2026

Zespół CERT Polska informuje o krytycznej podatności w FortiMail.Podatność, oznaczona jako CVE-2026-104286, umożliwia nieuwierzytelnionemu atakującemu zapisywanie dowolnych plików w systemie i w konsekwencji wykonanie dowolnego kodu, poprzez specjalnie sformatowane żądania HTTP. Wykorzystanie podatności wymaga dostępu do interfejsu zarządzania FortiMail. Producent potwierdza, że luka jest aktywnie wykorzystywana w atakach.Podatność dotyczy następujących wersji:FortiMail 8.0: 8.0.0 - 8.0.1FortiMail 7.6: 7.6.0 - 7.6.6FortiMail 7.4: 7.4.0 - 7.4.8FortiMail 7.2: 7.2.0 - 7.2.9Na moment publikacji...

Recent mention · NCSC Security Advisories

NCSC-2026-0398 [1.00] [M/H] Kwetsbaarheid verholpen in Fortinet FortiMail

NCSC Security Advisories · 02 Oct 2026

Fortinet heeft een kwetsbaarheid verholpen in FortiMail. FortiMail bevat een kritieke kwetsbaarheid (CVE-2026-104286) in de verwerking van bestandspaden, veroorzaakt door een combinatie van Path Traversal (CWE-22) en onvoldoende neutralisatie van NULL-bytes (CWE-158). Een niet-geauthenticeerde aanvaller kan via speciaal vervaardigde HTTP- of HTTPS-verzoeken willekeurige bestanden op het onderliggende systeem schrijven. De kwetsbaarheid wordt actief geëxploiteerd. Getroffen zijn FortiMail 7.2.0–7.2.9, 7.4.0–7.4.8, 7.6.0–7.6.6 en 8.0.0–8.0.1 waarbij de functionaliteit IBE (Identity Based...

Recent mention · Security Affairs

U.S. CISA adds Fortinet FortiMail flaw to its Known Exploited Vulnerabilities catalog

Security Affairs · 02 Oct 2026

U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds Fortinet FortiMail flaw to its Known Exploited Vulnerabilities catalog. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added a Fortinet FortiMail flaw, tracked as CVE-2026-104286 (CVSS score of 9.8), to its Known Exploited Vulnerabilities (KEV) catalog. The flaw is a path traversal vulnerability that can be triggered through […]

Recent mention · The Hacker News

Critical FortiMail Zero-Day Flaw Exploited in Attacks Allows Unauthenticated Arbitrary File Writes

The Hacker News · 02 Oct 2026

The U.S. Cybersecurity and Infrastructure Security Agency (CISA), on Thursday, added a critical security flaw impacting Fortinet FortiMail to its Known Exploited Vulnerabilities (KEV) catalog, following reports of active exploitation. The vulnerability, tracked as CVE-2026-104286 (CVSS score: 9.8), allows unauthenticated attackers to write arbitrary files on the underlying system. "An improper

Recent mention · FortiGuard

Improper limitation of a pathname to a restricted directory

FortiGuard · 01 Oct 2026

CVSSv3 Score: 9.8 An Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') [CWE-22] and Improper Neutralization of NULL Byte or NULL Character [CWE-158] vulnerability may allow an unauthenticated attacker to write arbitrary files on the underlying system via crafted HTTP or HTTPS requests.This has been reported to be exploited in the wild, customers are urged to apply the workaround below. Revised on 2026-10-01 00:00:00

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

ShadowForge-Cyber/CVE-2026-104286-POC

github · Created 2026-10-01 22:15:42 UTC · 0 stars · AI assessment 85%

Timeline

From disclosure to observed exploitation

  1. 11:20 UTC

    KEV confirmed by TheRegister

    Exploitation attested by an external source

  2. 09:21 UTC

    KEV confirmed by CERT Polska

    Exploitation attested by an external source

  3. 07:21 UTC

    KEV confirmed by Security Affairs

    Exploitation attested by an external source

  4. 06:21 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  5. 22:15 UTC

    Public PoC available

    Public proof-of-concept code published

  6. 20:01 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  7. 19:47 UTC

    KEV confirmed by FortiGuard

    Exploitation attested by an external source

  8. 19:38 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  9. 19:17 UTC

    CVE published

    Vulnerability disclosed publicly

  10. 19:12 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-104286

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-104286",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": null,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}