What is CVE-2026-39812?

CVE-2026-39812 is a medium-severity vulnerability in Fortinet Fortisandbox, classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2026-04-14.

How severe is CVE-2026-39812?

Medium severity. CVSS v3 base score is 4.8 out of 10.

XSS in Fortinet Fortisandbox

CVE-2026-39812

A improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Fortinet FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8, FortiSandbox 4.2 all versions, FortiSandbox PaaS 5.0.0 thr…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (9.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.

Affected products

Fortinet Fortisandbox — versions 5.0.0, 4.4.0, 4.2.1
Fortinet Fortisandbox_cloud — versions 5.0.4, 5.0.5
Fortinet Fortisandbox Paas — versions 5.0.0, 4.4.0, 4.2.1

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

psirt@fortinet.com (Vendor Advisory)

Frequently asked questions

What is CVE-2026-39812?: CVE-2026-39812 is a medium-severity vulnerability in Fortinet Fortisandbox, classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2026-04-14.
How severe is CVE-2026-39812?: Medium severity. CVSS v3 base score is 4.8 out of 10.