What is the CVSS score of CVE-2020-12812?

CVE-2020-12812 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 48.5%.

Which versions of SSL VPN are affected by CVE-2020-12812?

CVE-2020-12812 presents critical security risk rated CVSS 9.8. Successful exploitation could critically impact the confidentiality, integrity, and availability of affected systems.

Is CVE-2020-12812 being actively exploited?

Yes, CVE-2020-12812 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active in-the-wild exploitation. Immediate patching is required.

How to fix or mitigate CVE-2020-12812?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Monitor vendor channels for patch availability.

SSL VPN CVE-2020-12812

CRITICAL

Improper Handling of Case Sensitivity (CWE-178)

2020-07-24 psirt@fortinet.com

9.8

CVSS 3.1

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 26, 2026 - 11:19 vuln.today

Added to CISA KEV

Oct 24, 2025 - 12:53 cisa

CISA KEV

CVE Published

Jul 24, 2020 - 23:15 nvd

CRITICAL 9.8

DescriptionNVD

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.

AnalysisAI

FortiOS SSL-VPN contains an improper authentication vulnerability that allows users to bypass two-factor authentication by changing the case of their username, undermining MFA security controls.

Technical ContextAI

The CWE-178 case-sensitivity flaw means the 2FA lookup treats 'admin' and 'Admin' as different users. The password validation is case-insensitive (matching the AD backend), but the FortiToken association lookup is case-sensitive. Logging in with a different-case username passes password auth but skips the 2FA check.

Affected ProductsAI

Fortinet FortiOS 6.4.0 Fortinet FortiOS 6.2.0 to 6.2.3 Fortinet FortiOS 6.0.9 and below

RemediationAI

Upgrade FortiOS immediately. Review VPN authentication logs for case-variant login attempts. Ensure all remote access requires properly enforced MFA that cannot be bypassed through case manipulation.

CVE-2020-12812 vulnerability details – vuln.today

Back

SSL VPN CVE-2020-12812

CVSS VectorNVD

Lifecycle Timeline

DescriptionNVD

AnalysisAI

Technical ContextAI

Affected ProductsAI

RemediationAI

Share

External POC / Exploit Code