CVE-2026-39813Fortisandbox Vulnerability
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.
Published Apr 16, 2026 · Updated Jun 18, 2026
Key Facts
Patch immediately- CVE-2026-39813 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Fortisandbox (Fortinet), Fortisandboxcloud (Fortinet).
- It is exploited in the wild, listed in CIRCL KEV, Industry KEV feed since Jun 15, 2026. No public exploit code is known.
- EPSS estimates a 22% probability of exploitation in the next 30 days.
- Fixed versions are available, including Fortisandbox 4.4.9, Fortisandbox 5.0.6.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Scores
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
22%
Higher than 97.6% of all scored CVEs
Exploit maturity
Exploited (KEV)
ATLAS score
53/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Jun 15, 2026
60 days after publication
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Exploited (KEV)
Public exploit code
0
Proof-of-concept links
In-the-wild evidence
4
Reports of active use
Advisories And Exploit References
Description
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CIRCL KEV | Jun 15, 2026 | n/a | Not reported |
| Industry KEV feed | Jun 15, 2026 | n/a | Not reported |
Affected Products
20 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| FortisandboxFortinet | 4.4.0, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.4.6, 4.4.7 | 4.4.9 |
| FortisandboxcloudFortinet | 23.4, 24.1, 5.0.4, 5.0.5 | n/a |
Patched Releases
Fortisandbox
4.4.9, 5.0.6
Timeline
Publicly disclosed
Apr 16, 2026
Added to CIRCL KEV
Jun 15, 2026
Added to Industry KEV feed
Jun 15, 2026
Last updated
Jun 18, 2026
Weakness Type
- CWE-24 Path Traversal: '../filedir'
References
- advisoryfortiguard.fortinet.com · FG-IR-26-100
- advisoryhttps://fortiguard.fortinet.com/psirt/FG-IR-26-112
- advisoryUSOM advisory
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: Fortisandbox (Fortinet) versions 4.4.0, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.4.6, 4.4.7; Fortisandboxcloud (Fortinet) versions 23.4, 24.1, 5.0.4, 5.0.5. The full list is in the CVE brief.
It is exploited in the wild, listed in CIRCL KEV, Industry KEV feed since Jun 15, 2026.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Fortisandbox 4.4.9, Fortisandbox 5.0.6.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2026-39813 On Your Attack Surface?
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