What is CVE-2025-31366?

CVE-2025-31366 is a medium-severity vulnerability in Fortinet Fortios, classified under Cross-site Scripting. CVSS score: 4.7/10. Published 2025-10-14.

How severe is CVE-2025-31366?

Medium severity. CVSS v3 base score is 4.7 out of 10.

Is CVE-2025-31366 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in Fortinet Fortios

CVE-2025-31366

An Improper Neutralization of Input During Web Page Generation vulnerability [CWE-79] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4 all versions, FortiProxy 7.2 all versions, FortiProxy 7.0 all versions, FortiSASE 25.2.a may allow an unauthenticated attacker to perform a reflected cross site scripting (XSS) via crafted HTTP requests.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.004 (30.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Fortinet Fortios — versions 7.6.0, 7.4.0, 7.2.0
Fortinet Fortiproxy — versions 7.6.0, 7.4.0, 7.2.0
Fortinet Fortisase — versions 25.3.40, 25.2.a

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

https://fortiguard.fortinet.com/psirt/FG-IR-24-542 (Vendor Advisory)
0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

Frequently asked questions

What is CVE-2025-31366?: CVE-2025-31366 is a medium-severity vulnerability in Fortinet Fortios, classified under Cross-site Scripting. CVSS score: 4.7/10. Published 2025-10-14.
How severe is CVE-2025-31366?: Medium severity. CVSS v3 base score is 4.7 out of 10.
Is CVE-2025-31366 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.