CVE-2021-36166

Name: CVE-2021-36166
Creator: NVD / NIST
Published: 2022-03-01T18:15:08.24+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 1.41%

Last modified Jun 17, 2026

CVE-2021-36166 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. An improper authentication vulnerability in FortiMail before 7.0.1 may allow a remote attacker to efficiently guess one administrative account's authentication token by means of the observation of certain system's properties.. EPSS estimates a 1.41% chance of exploitation in the next 30 days.

Description

An improper authentication vulnerability in FortiMail before 7.0.1 may allow a remote attacker to efficiently guess one administrative account's authentication token by means of the observation of certain system's properties.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

1.41%

69.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-330

Affected Software

Vendor	Product	Versions
Fortinet	Fortimail	<= 5.4.12
Fortinet	Fortimail	>= 6.0.0, < 6.0.12
Fortinet	Fortimail	>= 6.2.0, < 6.2.8
Fortinet	Fortimail	>= 6.4.0, < 6.4.6
Fortinet	Fortimail	7.0.0

References

https://fortiguard.com/psirt/FG-IR-21-028Vendor Advisory
https://fortiguard.com/psirt/FG-IR-21-028Vendor Advisory

Timeline

Published: Mar 1, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-36166?

How severe is CVE-2021-36166?

CVE-2021-36166 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 1.41% probability of exploitation in the next 30 days.

How do I fix CVE-2021-36166?

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-2021-36166?

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

Scan your code now

Source: NVD / NIST