Is CVE-2021-36166 being actively exploited?

CVE-2021-36166 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2021-36166?

CVE-2021-36166 has a CVSS 3.1 base score of 9.8 (CRITICAL).

CVE-2021-36166

CRITICAL · CVSS 9.8EPSS 1.5%EU EUVD

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.

Key facts

CVSS score: 9.8 (v3.1)
Severity: CRITICAL
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-330
EPSS score: 1.5% (73th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2021-22787)
Published: March 1, 2022
NVD last modified: June 17, 2026
Status: Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-22787 in the EU Vulnerability Database. Last updated in EUVD on October 25, 2024.

View on the EU Vulnerability Database

Affected products

fortinet / fortimail
fortinet / fortimail

Certified products that may be affected

6 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

FortiMail 6.0 - Fortinet, Inc. - FIPS 140 3380 - historical
FortiMail-2000E/3000E - Fortinet, Inc. - FIPS 140 3363 - historical
Fortinet FortiMail 6.0 - Fortinet, Inc. - Common Criteria CCEVS-VR-10899-2019 - archived
FortiMail 5.2 - Fortinet, Inc. - FIPS 140 2539 - historical
FortiMail-1000D and FortiMail-3000D - Fortinet, Inc. - FIPS 140 2540 - historical

See all 6 in the Security Certifications Explorer.

References

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

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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