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

Source: https://junglewise.ai/threats/cve-2020-12812-fortinet-fortios-ssl-vpn-improper-authentication-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2020-12812 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

An improper authentication vulnerability in FortiOS SSL VPN allows a user to bypass two-factor authentication (FortiToken). By changing the case of their username during login, an attacker can successfully authenticate without being prompted for the second factor.

Technologies: [Fortinet FortiOS](https://junglewise.ai/threats/technologies/fortios). Vendors: [Fortinet](https://junglewise.ai/threats/vendors/fortinet).

## Quick answers

**Is CVE-2020-12812 exploited in the wild?** Yes. CVE-2020-12812 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2020-12812?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** Fortinet FortiOS 6.4.0, 6.2.0 to 6.2.3, 6.0.9 and below.

**Is there a fix for CVE-2020-12812?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2020-12812 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2020-12812?** Check whether you run Fortinet FortiOS. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

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

## Timeline

- 2020-07-24: disclosed: NVD Published Date
- 2021-11-03: kev added: Date added to CISA Known Exploited Vulnerabilities Catalog
- 2021-11-03: exploited: Reported exploited in the wild per advisory summary and CISA KEV entry.

## Related threats

- [Fortinet FortiOS authentication bypass in HA command execution](https://junglewise.ai/threats/cve-2026-126259-a-missing-authentication-for-critical-function-vulnerability-in)
- [Fortinet FortiOS stack buffer overflow in WAD proxy](https://junglewise.ai/threats/cve-2026-126258-a-stack-based-buffer-overflow-vulnerability-in-fortinet-fortios)
- [Fortinet FortiOS out-of-bounds read in kernel](https://junglewise.ai/threats/cve-2026-126256-a-out-of-bounds-read-vulnerability-in-fortinet-fortios-8-0-0)
- [Fortinet FortiOS path traversal authentication bypass in SSH daemon](https://junglewise.ai/threats/cve-2026-126255-a-path-traversal-filedir-vulnerability-in-fortinet-fortios-8-0-0)
- [Fortinet FortiOS numeric truncation error in BGP daemon](https://junglewise.ai/threats/cve-2026-126254-a-numeric-truncation-error-vulnerability-in-fortinet-fortios-8-0)