CVE-2021-26091

Name: CVE-2021-26091
Creator: NVD / NIST
Published: 2025-03-24T16:15:16.45+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.29%

Last modified Jun 17, 2026

CVE-2021-26091 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. A use of a cryptographically weak pseudo-random number generator vulnerability in the authenticator of the Identity Based Encryption service of FortiMail 6.4.0 through 6.4.4, and 6.2.0 through 6.2.7 may allow an unauthenticated attacker to infer parts of users authentication tokens and reset their credentials.. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

Description

A use of a cryptographically weak pseudo-random number generator vulnerability in the authenticator of the Identity Based Encryption service of FortiMail 6.4.0 through 6.4.4, and 6.2.0 through 6.2.7 may allow an unauthenticated attacker to infer parts of users authentication tokens and reset their credentials.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.29%

21.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-338

Affected Software

Vendor	Product	Versions
Fortinet	Fortimail	>= 6.2.0, < 6.4.5

References

https://fortiguard.com/advisory/FG-IR-21-031Vendor Advisory

Timeline

Published: Mar 24, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-26091?

How severe is CVE-2021-26091?

CVE-2021-26091 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26091?

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-2021-26091?

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

Scan your code now

Source: NVD / NIST