CVE-2020-12812: Fortinet FortiOS SSL VPN Improper Authentication Vulnerability

Critical severity, CVSS 9.8. Actively exploited: in CISA KEV since 2021-11-03. EPSS: 45.4% chance of exploitation in the next 30 days.

An improper authentication vulnerability in SSL VPN in FortiOS 6.4.0, 6.2.0 to 6.2.3, 6.0.9 and below may result in a user being able to log in successfully without being prompted for the second factor of authentication (FortiToken) if they changed the case of their username.

Affected products

• Fortinet FortiOS: before 6.0.10 (fixed in 6.0.10); from 6.2.0, before 6.2.4 (fixed in 6.2.4); version 6.4.0 only

Published 2020-07-24. Last modified 2026-10-02.