What is CVE-2020-15938?

CVE-2020-15938 is a medium-severity vulnerability in Fortinet Fortios. CVSS score: 4.0/10. Published 2021-03-04.

How severe is CVE-2020-15938?

Medium severity. CVSS v3 base score is 4.0 out of 10.

Vulnerability in Fortinet Fortios

CVE-2020-15938

When traffic other than HTTP/S (eg: SSH traffic, etc...) traverses the FortiGate in version below 6.2.5 and below 6.4.2 on port 80/443, it is not redirected to the transparent proxy policy for processing, as it doesn't have a valid HTTP header.

Published 2021-03-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.0 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (53.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 53.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.008 · change: +0.000

Affected products

Fortinet Fortios — versions FortiOS 6.4.2, 6.2.5
Fortinet Fortios

References

fortiguard.com/advisory/FG-IR-20-172 (Vendor Advisory)

Frequently asked questions

What is CVE-2020-15938?: CVE-2020-15938 is a medium-severity vulnerability in Fortinet Fortios. CVSS score: 4.0/10. Published 2021-03-04.
How severe is CVE-2020-15938?: Medium severity. CVSS v3 base score is 4.0 out of 10.