What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 45.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-24 · updated 2026-10-02
• Weakness: CWE-178

Description

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 (FortiGate): before 6.0.10; from 6.2.0 before 6.2.4; 6.4.0 — fixed in 6.0.10, 6.2.4

How to fix

Upgrade to a fixed version: Fortinet FortiOS (FortiGate) 6.0.10, 6.2.4. Check the vendor advisory for mitigations.

References

• https://fortiguard.com/psirt/FG-IR-19-283
• https://fortiguard.com/psirt/FG-IR-19-283
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-12812

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