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

> Attackers can bypass two-factor authentication in FortiOS SSL VPN by changing the case of their username, allowing unauthorized access.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Jul 2020
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-r9cj-q2hj-hfq9

## What is CVE-2020-12812?

CVE-2020-12812 is a high-severity authentication bypass vulnerability in Fortinet Fortios, published on 24 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-178 (Improper Handling of Case Sensitivity), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2020-12812?

It affects 1 product.


Products: Fortinet Fortios.

## How do I fix CVE-2020-12812?

No fix has been published for CVE-2020-12812 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 3 May 2022.

## Is CVE-2020-12812 being exploited?

Yes. Attackers have exploited CVE-2020-12812 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

## Other vulnerabilities in Fortinet Fortios

- [CVE-2024-23113](https://insights.sbomify.com/CVE-2024-23113/): Fortinet Multiple Products Format String (critical 9.8, exploited in the wild)
- [CVE-2022-40684](https://insights.sbomify.com/CVE-2022-40684/): Fortinet Multiple Products Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2024-55591](https://insights.sbomify.com/CVE-2024-55591/): Fortinet FortiOS and FortiProxy Authentication Bypass (critical 9.6, exploited in the wild)
- [CVE-2024-21762](https://insights.sbomify.com/CVE-2024-21762/): Fortinet FortiOS Out-of-Bound Write (critical 9.6, exploited in the wild)
- [CVE-2022-42475](https://insights.sbomify.com/CVE-2022-42475/): Fortinet FortiOS Heap-Based Buffer Overflow (critical 9.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-12812 and fix it if it is affected.

What it is: CVE-2020-12812 is a high-severity authentication bypass vulnerability in Fortinet Fortios, published on 24 Jul 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2020-12812 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Affected product: Fortinet Fortios. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-12812/ (Markdown: https://insights.sbomify.com/CVE-2020-12812/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-12812
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-12812
- OSV: https://osv.dev/vulnerability/CVE-2020-12812

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-12812/
Summaries are generated and may contain mistakes; the official description above is the record.