What is CVE-2020-6646?

CVE-2020-6646 is a medium-severity vulnerability in Fortinet Fortiweb, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2020-03-17.

How severe is CVE-2020-6646?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Fortinet Fortiweb

CVE-2020-6646

An improper neutralization of input vulnerability in FortiWeb allows a remote authenticated attacker to perform a stored cross site scripting attack (XSS) via the Disclaimer Description of a Replacement Message.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2020-03-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.0th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Fortinet Fortiweb — versions 6.3.0
Fortinet Fortiweb — versions FortiWeb 6.2.2

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

fortiguard.com/advisory/FG-IR-20-001 (Vendor Advisory)

Frequently asked questions

What is CVE-2020-6646?: CVE-2020-6646 is a medium-severity vulnerability in Fortinet Fortiweb, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2020-03-17.
How severe is CVE-2020-6646?: Medium severity. CVSS v3 base score is 5.4 out of 10.