dbcve.org
MeetingsApplication · Zoom

CVE-2021-33907

CRITICAL · 9.8 CVSS v3.1 Published 2021-09-27
Fix available
A fix is available. Upgrade to 5.3.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable 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
The Zoom Client for Meetings for Windows in all versions before 5.3.0 fails to properly validate the certificate information used to sign .msi files when performing an update of the client. This could lead to remote code execution in an elevated privileged context.

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

The Zoom Client for Meetings for Windows fails to properly validate certificate/signature information on .msi installer files during the update process in versions prior to 5.3.0. This allows potentially malicious MSI packages to be executed with elevated (SYSTEM) privileges during the automatic update mechanism, enabling remote code execution.

MitigationUpgrade Zoom Client for Meetings for Windows to version 5.3.0 or later which implements proper certificate validation for MSI files during updates. Deploy the update organization-wide via endpoint management tools.

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
MeetingsApplication
Affected:< 5.3.0

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

CVSS:3.1/AV:N/AC:L/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. Check installed Zoom version via UI
    Open the Zoom Client for Meetings application, click Help in the top menu, then select About Zoom. Note the version number displayed in the dialog box.
    Affected if The displayed version is any version prior to 5.3.0 (for example, 5.2.x, 5.1.x, 5.0.x, or earlier)
  2. Check installed Zoom version via PowerShell
    Run PowerShell and execute: Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ZoomUMX' | Select-Object DisplayVersion
    Affected if The DisplayVersion value returned is below 5.3.0
  3. Check Zoom version via executable
    Navigate to the Zoom installation directory (typically C:\Program Files\Zoom\bin\Zoom.exe or %USERPROFILE%\AppData\Roaming\Zoom\bin\Zoom.exe), right-click Zoom.exe, select Properties, and view the File version on the Details tab.
    Affected if The File version is below 5.3.0
  4. Confirm automatic update mechanism is in use
    In the Zoom client, go to Settings > General and look for the option labeled 'Automatically keep Zoom up to date' or check the registry key: Get-ItemProperty 'HKCU:\SOFTWARE\Zoom' -Name 'AutoUpdate' -ErrorAction SilentlyContinue
    Affected if Automatic updates are enabled and the installed version is below 5.3.0

Your environment is affected if the Zoom Client for Meetings for Windows is installed with any version lower than 5.3.0 and the automatic update feature is active.

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 5.3.0 or later
Fixed in 5.3.0
Interim mitigation

Upgrade Zoom Client for Meetings for Windows to version 5.3.0 or later which implements proper certificate validation for MSI files during updates. Deploy the update organization-wide via endpoint management tools.

Recommended fix High confidence

5.3.0 or later

  1. Open the Zoom desktop client and navigate to the profile picture or 'Help' menu
  2. Click on 'Check for Updates' to automatically update to the latest version
  3. Alternatively, download Zoom Client for Meetings version 5.3.0 or later from the official Zoom website (explore.zoom.us)
  4. Restart the Zoom application after the update completes
  5. Verify the installed version is 5.3.0 or higher by checking 'Help' > 'About Zoom'

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

Fix this in Meetings Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-33907 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-33907 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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