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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 3 May 2022. Known ransomware use
FortiosOperating system · Fortinet

CVE-2020-12812

CRITICAL · 9.8 CVSS v3.1 Published 2020-07-24
Fix available
A fix is available. Upgrade to 6.0.10 / 6.2.4 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Improper authentication vulnerability in FortiOS SSL VPN allows authentication bypass of FortiToken second-factor authentication when the username case is altered. The system incorrectly validates the primary credentials but fails to consistently enforce 2FA when username capitalization changes.

MitigationUpgrade FortiOS to patched version (6.4.1, 6.2.4, 6.0.10 or later) and verify that 2FA is consistently enforced regardless of username case formatting.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FortiosOperating system
Affected:< 6.0.10>= 6.2.0, < 6.2.4= 6.4.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check FortiOS version
    Run 'get system status' or 'diagnose sys flash list' via FortiOS CLI to retrieve the installed firmware version
    Affected if Version is < 6.0.10, or >= 6.2.0 and < 6.2.4, or = 6.4.0
  2. Confirm SSL VPN is configured
    Run 'get vpn ssl settings' in FortiOS CLI to check if SSL VPN is enabled
    Affected if SSL VPN is enabled on the FortiOS device
  3. Verify FortiToken is in use
    Run 'get user fortitoken' and 'get vpn ssl settings' to check if FortiToken two-factor authentication is configured for SSL VPN users
    Affected if FortiToken is configured as the second authentication factor for SSL VPN access
  4. Check username case handling policy
    Review SSL VPN authentication settings with 'get vpn ssl settings' and user configuration with 'get user' commands to verify how username case-sensitivity is handled
    Affected if System relies on case-sensitive username matching for FortiToken enforcement

User is affected if FortiOS version falls within < 6.0.10, >= 6.2.0 to < 6.2.4, or = 6.4.0, SSL VPN is enabled, and FortiToken two-factor authentication is used with case-sensitive username matching.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.0.10 / 6.2.4 or later
Fixed in 6.0.106.2.4
Interim mitigation

Upgrade FortiOS to patched version (6.4.1, 6.2.4, 6.0.10 or later) and verify that 2FA is consistently enforced regardless of username case formatting.

Recommended fix High confidence

FortiOS 6.0.10+, 6.2.4+, or 6.4.1+ (depending on your current branch)

  1. Identify the current FortiOS version by running 'get system status' or checking the FortiGate web UI
  2. Determine the appropriate upgrade path based on current version branch (6.0.x, 6.2.x, or 6.4.x)
  3. Backup the FortiGate configuration using 'execute backup config' command or via web UI
  4. Review the release notes for the target fixed version to understand changes and any special upgrade considerations
  5. Upgrade the FortiOS firmware to version 6.0.10 or higher for 6.0.x branch, 6.2.4 or higher for 6.2.x branch, or 6.4.1 or higher for 6.4.x branch
  6. After reboot, verify the FortiOS version is correct using 'get system status'
  7. Log into SSL VPN and confirm that FortiToken two-factor authentication is properly enforced regardless of username case variations
Caveat Review release notes for the target version as minor version upgrades may include behavioral changes; ensure compatibility with other Fortinet products in your environment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fortios Exploited in the wild — priority engagement
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,800
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-12812 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data