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FortiauthenticatorApplication · Fortinet

CVE-2026-21743

HIGH · 7.2 CVSS v3.1 Published 2026-02-10
Fix available
A fix is available. Upgrade to 6.6.7 or later.
See remediation →
78/100
Remediation priority · High
Remotely reachable 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
A missing authorization vulnerability in Fortinet FortiAuthenticator 6.6.0 through 6.6.6, FortiAuthenticator 6.5 all versions, FortiAuthenticator 6.4 all versions, FortiAuthenticator 6.3 all versions may allow a read-only user to make modification to local users via a file upload to an unprotected endpoint.

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 · moderate confidence

A missing authorization vulnerability in FortiAuthenticator allows authenticated read-only users to modify local user accounts by uploading files to an unprotected API endpoint, effectively bypassing role-based access controls designed to prevent modifications by non-admin users.

MitigationApply the vendor-supplied patch or upgrade FortiAuthenticator to a fixed version; additionally, restrict network access to the management interface to minimize exposure from compromised read-only accounts.

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
FortiauthenticatorApplication
Affected:>= 6.3.0, < 6.6.7

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/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. Identify FortiAuthenticator version
    Log into the FortiAuthenticator web GUI, go to System > Settings > Administration > System General, or run 'get system status' via CLI to retrieve the firmware version
    Affected if The installed version is 6.3.0 through 6.6.6 (any version >= 6.3.0 but < 6.6.7)
  2. Confirm presence of read-only user accounts
    Navigate to User Management > Local Users in the web GUI, or run 'fwmanager user list' via CLI, to see if any users with read-only or restricted roles exist
    Affected if There are any non-administrator user accounts configured with limited/modified roles
  3. Verify API endpoint access configuration
    Review API key configurations and API access policies under System > Administration > API Users in the web GUI, or check 'api-user' settings via CLI with 'show system api-user'
    Affected if API access is granted to read-only or non-administrator users without proper authorization controls enforced
  4. Check user modification capabilities
    Using a read-only user account, attempt to access the user modification API endpoint (POST /api/v1/local/users/) or upload functionality to confirm if unauthorized modifications are possible
    Affected if A read-only user can successfully modify or create local user accounts despite lacking administrative privileges

You are affected if your FortiAuthenticator version is 6.3.0 through 6.6.6 and you have non-administrator users configured with API access.

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 6.6.7 or later
Fixed in 6.6.7
Interim mitigation

Apply the vendor-supplied patch or upgrade FortiAuthenticator to a fixed version; additionally, restrict network access to the management interface to minimize exposure from compromised read-only accounts.

Recommended fix High confidence

FortiAuthenticator 6.6.7 or later (recommended: latest 6.6.x stable release)

  1. 1. Backup FortiAuthenticator configuration before upgrading
  2. 2. Download FortiAuthenticator version 6.6.7 or later from Fortinet support portal
  3. 3. Navigate to System > Firmware in FortiAuthenticator web UI
  4. 4. Upload and install the firmware version 6.6.7 or later
  5. 5. Verify the upgrade was successful by checking the firmware version in the dashboard
  6. 6. Confirm that read-only users can no longer modify local users via the file upload endpoint
Caveat Review FortiAuthenticator 6.6.7 release notes for any configuration or behavioral changes before upgrading, especially if upgrading from major versions 6.3/6.4/6.5

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

Fix this in Fortiauthenticator Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2026-21743 in production — separate from our analysis above.

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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