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CVE-2026-39813

Fortinet Fortisandbox•CRITICAL · CVSS 9.8• In the wild

What is CVE-2026-39813?

A path traversal: '../filedir' vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8 may allow attacker to escalation of privilege via specially crafted HTTP requests.

CVSS9.8 NVD 3.1

SeverityCRITICAL

Exploitation In the wild

EPSS22% · P98

Triage statusActive Exploit

ActionPatch within 48 hours

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWECWE-24

NVD published2026-04-14

NVD last modified2026-10-26

Timeline

2026-04-14Published to the U.S. National Vulnerability Database (NVD)
2026-06-17First covered in a defend.network daily briefing
2026-10-26NVD record last updated

Affected product

Fortinet Fortisandbox

Remediation Steps

Apply the vendor security update for Fortinet Fortisandbox as a priority.
Restrict network exposure of the affected service to trusted sources until patched.
Review logs and detections for indicators of exploitation.
Confirm fixed versions against the official vendor advisory before deploying.

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 3 of June 2026 (June 15 – 21)
Fortinet actively exploited; Rokarolla targets 217 banking apps; Google Vertex AI flaw (2026-06-17)

Related vulnerabilities

CVE-2026-25089 – Fortinet FortiSandbox (same product)
CVE-2026-39808 – Fortinet FortiSandbox (same product)
CVE-2026-104286 – Fortinet FortiMail (same vendor)
CVE-2025-61624 – Fortinet Multiple Products (same vendor)
CVE-2026-35616 – Fortinet FortiClient EMS (same vendor)
CVE-2025-68686 – Fortinet FortiOS (same vendor)

Fortinet: 32 known exploited vulnerabilities (CISA KEV) →

Browse all tracked CVEs in the defend.network CVE database →

🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.