CVE-2020-12812
CRITICALCISA KEVEPSS 99th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
Fortinet FortiOS SSL VPN Improper Authentication Vulnerability
Fortinet FortiOS SSL VPN contains an improper authentication vulnerability that may allow a user to login successfully without being prompted for the second factor of authentication (FortiToken) if they change the case in their username.
Apply updates per vendor instructions.
Remediation due: 2022-05-03
Associated with ransomware campaigns
References
Related Vulnerabilities
Other CWE-178 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-27636 | Medium | 5.6 | 81% | - | Fix |
| CVE-2021-24347 | High | 8.8 | 54% | - | Fix |
| CVE-2003-0411 | High | 7.5 | 25% | - | - |
| CVE-2018-9845 | Critical | 9.8 | 13% | - | Fix |
| CVE-2001-0766 | Critical | 9.8 | 8.2% | - | - |
| CVE-1999-0239 | High | 7.5 | 7.4% | - | - |
Common questions
How do I fix CVE-2020-12812?
Upgrade fortios to 6.2.4 or later.
Is CVE-2020-12812 being actively exploited?
Yes. CVE-2020-12812 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. CISA has also linked it to known ransomware campaigns. US federal agencies were required to remediate it by 2022-05-03. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2020-12812?
CVE-2020-12812 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2020-12812 affect?
Published advisories record a fix for fortios (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2020-12812
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-24.