FortiMail 6.x Weak PRNG in IdB Encryption Auth leading to credential reset
CVE-2021-26091 Published on March 24, 2025
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.
Vulnerability Analysis
CVE-2021-26091 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
What is a PRNG Vulnerability?
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.
CVE-2021-26091 has been classified to as a PRNG vulnerability or weakness.
Products Associated with CVE-2021-26091
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Affected Versions
Fortinet FortiMail:- Version 6.4.0, <= 6.4.4 is affected.
- Version 6.2.0, <= 6.2.9 is affected.
- Version 6.2.0 and below 6.2.* is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.