CVE-2021-26103

Name: CVE-2021-26103
Creator: NVD / NIST
Published: 2021-12-08T12:15:07.677+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 0.42%

Last modified Jun 17, 2026

CVE-2021-26103 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. An insufficient verification of data authenticity vulnerability (CWE-345) in the user interface of FortiProxy verison 2.0.3 and below, 1.2.11 and below and FortiGate verison 7.0.0, 6.4.6 and below, 6.2.9 and below of SSL VPN portal may allow a remote, unauthenticated attacker to conduct a cross-site request forgery (CSRF) attack . Only SSL VPN in web mode or full mode are impacted by this vulnerability.. EPSS estimates a 0.42% chance of exploitation in the next 30 days.

Description

An insufficient verification of data authenticity vulnerability (CWE-345) in the user interface of FortiProxy verison 2.0.3 and below, 1.2.11 and below and FortiGate verison 7.0.0, 6.4.6 and below, 6.2.9 and below of SSL VPN portal may allow a remote, unauthenticated attacker to conduct a cross-site request forgery (CSRF) attack . Only SSL VPN in web mode or full mode are impacted by this vulnerability.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

0.42%

33.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-345

Affected Software

Vendor	Product	Versions
Fortinet	Fortiproxy	>= 1.2.0, <= 1.2.11
Fortinet	Fortiproxy	>= 2.0.0, <= 2.0.3
Fortinet	Fortios	>= 5.6.0, <= 5.6.14
Fortinet	Fortios	>= 6.0.0, <= 6.0.13
Fortinet	Fortios	>= 6.2.0, <= 6.2.9
Fortinet	Fortios	>= 6.4.0, <= 6.4.6
Fortinet	Fortios	7.0.0

References

https://fortiguard.com/advisory/FG-IR-20-158Patch, Vendor Advisory
https://fortiguard.com/advisory/FG-IR-20-158Patch, Vendor Advisory

Timeline

Published: Dec 8, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26103?

How severe is CVE-2021-26103?

CVE-2021-26103 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.42% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26103?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26103?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST