Treat CVE-2026-104286 as urgent: CERT-FR reported on 2026-10-02 that Fortinet says the flaw is being actively exploited. Identify your exact FortiMail build, check it against the current Fortinet advisory FG-IR-26-175, and follow that advisory’s release-specific instructions before changing a production system. The available source information does not establish a CVE-specific workaround, patch procedure, or verification command.
What does CVE-2026-104286 let an attacker do?
NVD describes the vulnerability as a path traversal that could let an unauthenticated attacker write arbitrary files to the underlying system by sending crafted HTTP or HTTPS requests. NVD records Fortinet’s CNA severity as 9.8 — Fortinet, 2026 (CVSS 3.1, Critical; AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). NVD published its record on 2026-10-01 and modified it on 2026-10-02.
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CERT-FR’s 2026-10-02 notice says Fortinet reports active exploitation. If your appliance may be affected, prioritize checking its build and following Fortinet’s current guidance; if you suspect an intrusion, use your incident-response process rather than treating an upgrade alone as proof that the system is clean.
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The available version information is not consistent enough to identify every affected build safely. NVD’s description gives one version range, while its Fortinet-attributed product table lists narrower ranges for some branches and includes 7.0. Do not infer that a build is safe—or vulnerable—from a single summary range. Compare the appliance’s exact installed version and build with the current Fortinet FG-IR-26-175 advisory.
#1 Best Overall
- FortiMail is a top-rated secure email gateway that stops volume-based and targeted cyber threats to help secure the dynamic enterprise attack surface, prevents the loss of sensitive data and helps
- High performance physical and virtual appliances deploy on-site or in the public cloud to serve any size organization - from small businesses to carriers, service providers, and large enterprises
- Threat Prevention Powerful antispam and antimalware, are complemented by advanced techniques like outbreak protection, content disarm and reconstruction, sandbox analysis, impersonation detection
- Data Protection Robust data loss prevention, identitybased email encryption and archiving help prevent the inadvertent loss of sensitive information and maintain compliance with corporate and
- Security Fabric Integration Integrations with Fortinet products as well as third-party components help customers adopt a proactive approach to security by sharing IoCs across a seamless Security
| FortiMail branch | Fix version reported by CERT-FR | Availability in the dated source |
|---|---|---|
| 7.4 | 7.4.9 | CERT-FR listed it as upcoming on 2026-10-02; current availability is not established by that notice. |
| 7.6 | 7.6.7 | CERT-FR listed it as upcoming on 2026-10-02; current availability is not established by that notice. |
| 8.0 | 8.0.2 | CERT-FR listed it as upcoming on 2026-10-02; current availability is not established by that notice. |
| 7.0 | Not stated in CERT-FR’s summary | Check the current Fortinet advisory for the branch’s status and remediation. |
These are fix versions named as upcoming in CERT-FR’s notice, not confirmation that they are currently available or suitable for every deployment. Fortinet’s live advisory is the authority for affected builds, fixed releases, availability, and any branch-specific direction.
How do I patch FortiMail safely?
- Record the installed version and build. Use the appliance’s supported administration interface or documented method to identify the precise version; do not rely only on the major branch number.
- Open Fortinet’s current FG-IR-26-175 advisory. Confirm whether that exact build is affected and which fixed release Fortinet currently specifies for its branch.
- Read the release-specific FortiMail upgrade documentation. Follow Fortinet’s supported upgrade path and any backup, sequencing, or preparation precautions it prescribes. Do not jump to a version solely because it appears in the dated CERT-FR summary.
- Apply the vendor-directed upgrade. Use the instructions for your appliance and target release. The available source information does not establish a CVE-specific patch command or step-by-step procedure, so this article does not supply one.
No CVE-specific workaround was established in the available source information. If you cannot upgrade immediately, check FG-IR-26-175 for any current mitigation rather than relying on an assumed workaround.
Rank #2
- FortiMail is a top-rated secure email gateway that stops volume-based and targeted cyber threats to help secure the dynamic enterprise attack surface, prevents the loss of sensitive data and helps
- High performance physical and virtual appliances deploy on-site or in the public cloud to serve any size organization - from small businesses to carriers, service providers, and large enterprises
- Threat Prevention Powerful antispam and antimalware, are complemented by advanced techniques like outbreak protection, content disarm and reconstruction, sandbox analysis, impersonation detection
- Data Protection Robust data loss prevention, identitybased email encryption and archiving help prevent the inadvertent loss of sensitive information and maintain compliance with corporate and
- Security Fabric Integration Integrations with Fortinet products as well as third-party components help customers adopt a proactive approach to security by sharing IoCs across a seamless Security
How can I verify the fix?
After the upgrade, identify the resulting FortiMail version and build using a vendor-supported method and compare it with the fixed release listed in the current FG-IR-26-175 table. Treat that version match as confirmation of the software update—not as evidence that no attacker accessed or altered the appliance. No CVE-specific verification command or test was established in the available source information; use any post-upgrade checks Fortinet documents in the advisory or release documentation.
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What if I suspect FortiMail was compromised?
Because CERT-FR reports active exploitation, suspected compromise requires incident handling as well as remediation. Consult FG-IR-26-175 for Fortinet’s indicators of compromise and response guidance, and follow your organization’s incident-response process. Preserve and review relevant evidence under that process, and do not infer that an appliance is uncompromised merely because it is now running a fixed build. The available source information does not establish specific log paths, indicator values, or containment commands.
Quick Recap
Rank #4
- FORTINET FortiGate-1801F Network Security Appliance (FG-1801F)
- The FortiGate 1801F delivers high performance next generation firewall (NGFW) capabilities for large enterprises and service providers. With multiple high-speed interfaces, high-port density and highthroughput, ideal deployments are at the enterprise edge, hybrid and hyperscale data center core and across internal segments. Leverage industry-leading IPS, SSL inspection and advanced threat protection to optimize your network’s performance.
- Custom SPU processors deliver the power you need to detect malicious content at multi-Gigabit speeds; Other security technologies cannot protect against today’s wide range of content and connection-based threats because they rely on general-purpose CPUs, causing a dangerous performance gap.
- Hardware: 198 Gbps | IPS: 13 Gbps | NGFW: 11 Gbps | Threat Protection: 9.1 Gbps; Interface: 4 x 40 GE QSFP+ slots, 12 x 25 GE SFP28 /10GE SFP+ slots, 2x10GE SFP+ HA slots, 8 x GE SFP slots, 18 x GE RJ45 ports, SPU NP7 and CP9 hardware accelerated, 2x 1TB on board SSD storage
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