What is CVE-2021-26091?

CVE-2021-26091 is a medium-severity vulnerability in Fortinet Fortimail, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 6.9/10. Published 2025-03-24.

How severe is CVE-2021-26091?

Medium severity. CVSS v3 base score is 6.9 out of 10.

Vulnerability in Fortinet Fortimail

CVE-2021-26091

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…

EPSS: 0.003 (50.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:U/RC:C.

Affected products

Fortinet Fortimail — versions 6.4.0, 6.2.0

Weakness classification (CWE)

CWE-338 — Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

References

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

Frequently asked questions

What is CVE-2021-26091?: CVE-2021-26091 is a medium-severity vulnerability in Fortinet Fortimail, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 6.9/10. Published 2025-03-24.
How severe is CVE-2021-26091?: Medium severity. CVSS v3 base score is 6.9 out of 10.