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ForticlientApplication · Fortinet

CVE-2021-41028

HIGH · 7.5 CVSS v3.1 Published 2021-12-16
Fix available
A fix is available. Upgrade to after 6.4.6 or later.
See remediation →
80/100
Remediation priority · High
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
A combination of a use of hard-coded cryptographic key vulnerability [CWE-321] in FortiClientEMS 7.0.1 and below, 6.4.6 and below and an improper certificate validation vulnerability [CWE-297] in FortiClientWindows, FortiClientLinux and FortiClientMac 7.0.1 and below, 6.4.6 and below may allow an unauthenticated and network adjacent attacker to perform a man-in-the-middle attack between the EMS and the FCT via the telemetry protocol.

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

This vulnerability combines two issues: a hard-coded cryptographic key (CWE-321) in FortiClientEMS versions 7.0.1 and below, 6.4.6 and below, and improper certificate validation (CWE-297) in FortiClient for Windows, Linux, and Mac (same version ranges). These flaws allow an unauthenticated, network-adjacent attacker to intercept and manipulate the telemetry communication between the EMS server and FortiClient endpoints via man-in-the-middle attacks.

MitigationUpgrade FortiClientEMS and all FortiClient installations (Windows, Linux, Mac) to versions 7.0.2/6.4.7 or later. If immediate patching is not possible, restrict network access to the telemetry port and implement additional network segmentation to limit adjacent attacker capability.

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
ForticlientApplication
Affected:>= 6.0.0, <= 6.0.9>= 6.2.0, <= 6.2.9>= 6.4.0, <= 6.4.6= 7.0.0= 7.0.1
Forticlient Endpoint Management ServerApplication
Affected:>= 6.2.0, <= 6.2.9>= 6.4.0, <= 6.4.6= 7.0.0= 7.0.1

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
Adjacent
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:H/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. Identify installed FortiClient version on Windows
    Open Control Panel > Programs and Features, look for 'FortiClient' in the installed programs list, or run 'reg query "HKLM\SOFTWARE\Fortinet\FortiClient" /v Version' in Command Prompt
    Affected if The version shown is 6.0.0-6.0.9, 6.2.0-6.2.9, 6.4.0-6.4.6, 7.0.0, or 7.0.1
  2. Identify installed FortiClient version on Linux
    Run 'dpkg -l | grep forticlient' or 'rpm -qa | grep -i forticlient' in terminal, or check /opt for FortiClient installation directory
    Affected if The version shown is 6.0.0-6.0.9, 6.2.0-6.2.9, 6.4.0-6.4.6, 7.0.0, or 7.0.1
  3. Identify installed FortiClient version on macOS
    Open Finder > Applications and check the FortiClient.app version via Get Info, or run 'defaults read /Applications/FortiClient.app/Contents/Info.plist CFBundleVersion' in terminal
    Affected if The version shown is 6.0.0-6.0.9, 6.2.0-6.2.9, 6.4.0-6.4.6, 7.0.0, or 7.0.1
  4. Identify FortiClientEMS server version
    Log into the EMS web console and check the dashboard for the version number, or run 'cat /var/opt/forticlient-ems/VERSION' on the EMS server if shell access is available
    Affected if The EMS version is 6.2.0-6.2.9, 6.4.0-6.4.6, 7.0.0, or 7.0.1
  5. Determine if FortiClient telemetry is active
    Check if FortiClient is configured to connect to an EMS server - on Windows check the FortiClient GUI 'Endpoint Control' panel for 'Connected' status, or check registry key 'HKLM\SOFTWARE\Fortinet\FortiClient\SCEP\Server'
    Affected if FortiClient is managed by an EMS and shows an active connection to the EMS server, indicating telemetry communication is in use

You are affected if any FortiClient endpoint (Windows/Linux/Mac) or FortiClientEMS server in your environment is running version 6.0.0-6.0.9, 6.2.0-6.2.9, 6.4.0-6.4.6, 7.0.0, or 7.0.1 and telemetry to an EMS server is enabled.

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 a release after 6.4.6
Interim mitigation

Upgrade FortiClientEMS and all FortiClient installations (Windows, Linux, Mac) to versions 7.0.2/6.4.7 or later. If immediate patching is not possible, restrict network access to the telemetry port and implement additional network segmentation to limit adjacent attacker capability.

Recommended fix Moderate confidence

FortiClient: 6.4.7+ or 7.0.2+ | FortiClientEMS: 6.4.7+ or 7.0.2+

  1. 1. Identify the currently installed FortiClient version by opening FortiClient and checking 'About' or using the --version flag
  2. 2. Identify the currently installed FortiClientEMS version from the EMS server console or management interface
  3. 3. For FortiClient: upgrade to version 6.4.7 or later, or 7.0.2 or later
  4. 4. For FortiClientEMS: upgrade to version 6.4.7 or later, or 7.0.2 or later
  5. 5. Verify the upgrade was successful by confirming the new version numbers
  6. 6. Test the telemetry connection between FortiClient and EMS to ensure proper operation
Caveat Review Fortinet release notes for version 6.4.7 and 7.0.2 for any configuration or feature changes that may affect existing deployments

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

Fix this in Forticlient Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2021-41028 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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