FusionApplication · VMware
CVE-2020-3957
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 · uneditedVMware Fusion (11.x before 11.5.5), VMware Remote Console for Mac (11.x and prior) and VMware Horizon Client for Mac (5.x and prior) contain a local privilege escalation vulnerability due to a Time-of-check Time-of-use (TOCTOU) issue in the service opener. Successful exploitation of this issue may allow attackers with normal user privileges to escalate their privileges to root on the system where Fusion, VMRC and Horizon Client are installed.
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 confidenceVMware Fusion, VMRC, and Horizon Client for Mac contain a TOCTOU race condition in the service opener component. An attacker with normal user privileges can exploit the time gap between checking file/directory permissions and using them to escalate to root privileges on the host system.
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
FusionApplication
>= 11.0.0, < 11.5.5
Horizon ClientApplication
<= 5.4.0
Remote ConsoleApplication
<= 11.0.1CVSS 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
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed VMware products on macOSCheck the /Applications folder for VMware Fusion, VMware Horizon Client, or VMware Remote Console. Use terminal: ls /Applications | grep -i vmwareAffected if Any of these three VMware products are found installed on the system
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Get the installed version of VMware FusionRun: defaults read /Applications/VMware\ Fusion.app/Contents/Info CFBundleVersionAffected if Fusion is installed and version is 11.0.0 or higher but less than 11.5.5
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Get the installed version of VMware Horizon ClientRun: defaults read /Applications/VMware\ Horizon\ Client.app/Contents/Info CFBundleVersionAffected if Horizon Client is installed and version is 5.4.0 or lower
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Get the installed version of VMware Remote ConsoleRun: defaults read /Applications/VMware\ Remote\ Console.app/Contents/Info CFBundleVersionAffected if VMRC is installed and version is 11.0.1 or lower
The environment is affected if any of these VMware products are installed with a version matching the specified ranges (Fusion 11.0.0 to <11.5.5, Horizon Client <=5.4.0, VMRC <=11.0.1) on macOS.
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 data11.5.5
Apply vendor patches: VMware Fusion 11.5.5 or later, and updated versions of VMRC and Horizon Client for Mac as specified in VMware security advisory VMSA-2020-0007.
Fix this in Fusion
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3957 — 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-2020-3957 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
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