CVE-2022-26122: Fortinet Antivirus Engine

High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days.

An insufficient verification of data authenticity vulnerability [CWE-345] in FortiClient, FortiMail and FortiOS AV engines version 6.2.168 and below and version 6.4.274 and below may allow an attacker to bypass the AV engine via manipulating MIME attachment with junk and pad characters in base64.

Affected products

• Fortinet Antivirus Engine: version 0.4.23 only; version 2.0.49 only; version 2.0.60 only; version 4.4.54 only; version 6.33 only; version 6.137 only; …
• Fortinet FortiMail: from 6.0.0, up to and including 6.0.12; from 6.2.0, up to and including 6.2.9; from 6.4.0, up to and including 6.4.6; from 7.0.0, up to and including 7.0.2; version 4.1.0 only
• Fortinet FortiOS: from 6.0.0, up to and including 6.0.15; from 6.2.0, up to and including 6.2.11; from 6.4.0, up to and including 6.4.10; from 7.0.0, up to and including 7.0.6; version 7.2.0 only

Published 2022-11-02. Last modified 2026-06-17.