ForticlientApplication · Fortinet
CVE-2020-9290
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 · uneditedAn Unsafe Search Path vulnerability in FortiClient for Windows online installer 6.2.3 and below may allow a local attacker with control over the directory in which FortiClientOnlineInstaller.exe and FortiClientVPNOnlineInstaller.exe resides to execute arbitrary code on the system via uploading malicious Filter Library DLL files in that directory.
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 confidenceFortiClient online installer executables (FortiClientOnlineInstaller.exe and FortiClientVPNOnlineInstaller.exe) use an unsafe DLL search path that loads Filter Library DLLs from the current working directory without validating the full path. A local attacker with control over the installation directory can place malicious DLLs that get loaded with the installer privileges, achieving arbitrary code execution.
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
<= 6.2.3
Forticlient Virtual Private NetworkApplication
<= 6.2.3CVSS 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
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/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 checksWork through these to decide whether this CVE applies to you.
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Check if FortiClient is installedLook for FortiClient installation directories such as C:\Program Files\Fortinet\ or C:\Program Files (x86)\Fortinet\. Also check Windows Registry under HKLM\SOFTWARE\Fortinet or HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall for FortiClient entries.Affected if FortiClient or FortiClient VPN software is found on the system
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Identify installed FortiClient versionLocate the installed FortiClient application and check its version. In the installation directory, look for version information in file properties of the main executable (FortiClient.exe) or check Add/Remove Programs for the version number.Affected if Installed version is 6.2.3 or earlier (any version <= 6.2.3)
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Locate vulnerable installer executablesSearch for FortiClientOnlineInstaller.exe and FortiClientVPNOnlineInstaller.exe on the system. These are typically found in download folders, temporary directories, or the original installation source location.Affected if These specific installer files exist on the system and are version 6.2.3 or earlier
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Check DLL loading behavior (manual verification)Attempt to run the installer from a directory where you have write permissions, then monitor DLL loads using Process Monitor (procmon.exe) from Sysinternals. Look for the installer loading DLLs from the current working directory rather than system paths.Affected if The installer loads DLLs from its current working directory without validating the full path (Filter Library DLLs from local directory)
The system is affected if FortiClient or FortiClient VPN version 6.2.3 or earlier is installed, or if the vulnerable installer executables (FortiClientOnlineInstaller.exe or FortiClientVPNOnlineInstaller.exe) of those versions are present on the system.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataEnsure FortiClient is updated to version 6.2.4 or later. As a compensating control, only run installers from trusted, attacker-controlled-inaccessible directories and verify the installation directory has appropriate access controls to prevent unauthorized file placement.
Fix this in Forticlient
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-9290 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-9290 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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