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 through 5.0.5, FortiSandbox PaaS 4.4.0 through 4.4.8, FortiSandbox PaaS 4.2 all versions may allow attacker to execute unauthorized code or commands via <insert attack vector here>

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (9.0th 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.