CVE-2026-104286: in the CISA KEV catalogue
Fortinet FortiMail Path Traversal Vulnerability. CISA added CVE-2026-104286 to the Known Exploited Vulnerabilities catalogue on 2026-10-01 with a default due date of 2026-10-04. Known ransomware campaign use: Unknown. Forensic triage flag: Yes.
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 description)
- Vendor / product
- Fortinet FortiMail
- CWE
- CWE-22, CWE-158
- CISA 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. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- EPSS
- 4.6%, percentile 91 (scored 2026-11-03)
EPSS puts about 4.6 in 100 odds (4.6%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 91% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
- https://fortiguard.fortinet.com/psirt/FG-IR-26-175
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-104286
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2026-104286 in the CISA KEV catalogue?
Yes. CISA added CVE-2026-104286 (Fortinet FortiMail Path Traversal Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2026-10-01. CISA's default due date for it is 2026-10-04.
Is CVE-2026-104286 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2026-104286. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2026-104286?
CISA's 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. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2026-104286