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ForticlientApplication · Fortinet

CVE-2021-22127

HIGH · 8.0 CVSS v3.1 Published 2022-04-06
Fix available
A fix is available. Upgrade to 6.2.9 / 6.4.3 or later.
See remediation →
83/100
Remediation priority · High
No privileges

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 input validation vulnerability in FortiClient for Linux 6.4.x before 6.4.3, FortiClient for Linux 6.2.x before 6.2.9 may allow an unauthenticated attacker to execute arbitrary code on the host operating system as root via tricking the user into connecting to a network with a malicious name.

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 input validation in FortiClient for Linux versions 6.4.x before 6.4.3 and 6.2.x before 6.2.9 allows an unauthenticated attacker to execute arbitrary code as root by tricking users into connecting to a network with a malicious name (e.g., malicious WiFi SSID).

MitigationUpgrade FortiClient for Linux to version 6.4.3 or later (6.2.x branch to 6.2.9 or later) to remediate this vulnerability.

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:< 6.2.9>= 6.4.0, < 6.4.3

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
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:R/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 FortiClient for Linux version
    Run 'forticlient --version' or 'rpm -q forticlient' or 'dpkg -l forticlient' to retrieve the installed version number
    Affected if The version is 6.2.x before 6.2.9, or 6.4.0 through 6.4.2 (versions below 6.4.3)
  2. Confirm the vulnerable feature is in use
    Verify if FortiClient VPN or WiFi protection module is enabled or configured. Check for active VPN profiles or WiFi protection settings in the FortiClient configuration
    Affected if The VPN or WiFi protection feature is active and users can connect to arbitrary networks
  3. Identify network exposure
    Review whether users have the ability to connect to untrusted WiFi networks through FortiClient-protected interfaces
    Affected if Users can connect to arbitrary WiFi SSIDs (such as on laptops or mobile devices) while FortiClient is running

You are affected if FortiClient for Linux version is 6.2.x before 6.2.9 or 6.4.x before 6.4.3 AND the VPN or WiFi protection feature is enabled, allowing connection to untrusted networks.

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 6.2.9 / 6.4.3 or later
Fixed in 6.2.96.4.3
Interim mitigation

Upgrade FortiClient for Linux to version 6.4.3 or later (6.2.x branch to 6.2.9 or later) to remediate this vulnerability.

Recommended fix High confidence

FortiClient for Linux 6.2.9 (for 6.2.x branch) or FortiClient for Linux 6.4.3 (for 6.4.x branch)

  1. 1. Identify the current FortiClient for Linux version by running: fcui --version or checking the FortiClient GUI About section
  2. 2. Determine which upgrade path applies: if version is 6.2.x, upgrade to 6.2.9; if version is 6.4.x, upgrade to 6.4.3
  3. 3. Download the appropriate fixed version from the Fortinet FortiGuard download center (https://www.fortiguard.com/products/forticlient) or your Fortinet support portal
  4. 4. Stop any running FortiClient processes: pkill -f forticlient
  5. 5. Install the updated FortiClient for Linux package using your distribution's package manager (dpkg for Debian/Ubuntu, rpm for RHEL/CentOS, or the FortiClient installer directly)
  6. 6. Verify the installation was successful and the version matches the target fixed release
  7. 7. Restart the FortiClient service if needed

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

Fix this in Forticlient Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
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Scan for this in your stack

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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-2021-22127 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