What is CVE-2021-26091?

CVE-2021-26091 is a high-severity vulnerability in Fortinet Fortimail, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 7.5/10. Published 2025-03-24.

How severe is CVE-2021-26091?

High severity. CVSS v3 base score is 7.5 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 infer parts of users authentication tokens and reset their credentials.

EPSS: 0.003 (22.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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

psirt@fortinet.com (Vendor Advisory)

Frequently asked questions

What is CVE-2021-26091?: CVE-2021-26091 is a high-severity vulnerability in Fortinet Fortimail, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 7.5/10. Published 2025-03-24.
How severe is CVE-2021-26091?: High severity. CVSS v3 base score is 7.5 out of 10.