dbcve.org
MeetingsApplication · Zoom

CVE-2021-34423

CRITICAL · 9.8 CVSS v3.1 Published 2021-11-24
Fix available
A fix is available. Upgrade to 5.0.1 / 5.7.6.1922 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit 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
A buffer overflow vulnerability was discovered in Zoom Client for Meetings (for Android, iOS, Linux, macOS, and Windows) before version 5.8.4, Zoom Client for Meetings for Blackberry (for Android and iOS) before version 5.8.1, Zoom Client for Meetings for intune (for Android and iOS) before version 5.8.4, Zoom Client for Meetings for Chrome OS before version 5.0.1, Zoom Rooms for Conference Room (for Android, AndroidBali, macOS, and Windows) before version 5.8.3, Controllers for Zoom Rooms (for Android, iOS, and Windows) before version 5.8.3, Zoom VDI Windows Meeting Client before version 5.8.4, Zoom VDI Azure Virtual Desktop Plugins (for Windows x86 or x64, IGEL x64, Ubuntu x64, HP ThinPro OS x64) before version 5.8.4.21112, Zoom VDI Citrix Plugins (for Windows x86 or x64, Mac Universal Installer & Uninstaller, IGEL x64, eLux RP6 x64, HP ThinPro OS x64, Ubuntu x64, CentOS x 64, Dell ThinOS) before version 5.8.4.21112, Zoom VDI VMware Plugins (for Windows x86 or x64, Mac Universal Installer & Uninstaller, IGEL x64, eLux RP6 x64, HP ThinPro OS x64, Ubuntu x64, CentOS x 64, Dell ThinOS) before version 5.8.4.21112, Zoom Meeting SDK for Android before version 5.7.6.1922, Zoom Meeting SDK for iOS before version 5.7.6.1082, Zoom Meeting SDK for macOS before version 5.7.6.1340, Zoom Meeting SDK for Windows before version 5.7.6.1081, Zoom Video SDK (for Android, iOS, macOS, and Windows) before version 1.1.2, Zoom On-Premise Meeting Connector Controller before version 4.8.12.20211115, Zoom On-Premise Meeting Connector MMR before version 4.8.12.20211115, Zoom On-Premise Recording Connector before version 5.1.0.65.20211116, Zoom On-Premise Virtual Room Connector before version 4.4.7266.20211117, Zoom On-Premise Virtual Room Connector Load Balancer before version 2.5.5692.20211117, Zoom Hybrid Zproxy before version 1.0.1058.20211116, and Zoom Hybrid MMR before version 4.6.20211116.131_x86-64. This can potentially allow a malicious actor to crash the service or application, or leverage this vulnerability to execute arbitrary code.

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
How this class of weakness works · CWE-120

A fixed-size buffer is filled without checking the length of the incoming data, so it overflows into neighbouring memory. This is the classic overflow attackers use to overwrite return addresses and hijack execution. The fix is strict length checks and safe, bounded string and memory functions.

General guidance for the classic buffer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:< 5.8.3< 5.8.4
Meetings For BlackberryApplication
Affected:< 5.8.1
Meetings For IntuneApplication
Affected:< 5.8.4
Meetings For Chrome OsWeb browser
Affected:< 5.0.1
Rooms For Conference RoomsApplication
Affected:< 5.8.3
Controllers For Zoom RoomsApplication
Affected:< 5.8.3
Virtual Desktop InfrastructureApplication
Affected:< 5.8.4
Android Meeting SdkApplication
Affected:< 5.7.6.1922

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

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 5.0.1 / 5.7.6.1922 / 5.8.1 or later
Fixed in 5.0.15.7.6.19225.8.1
Recommended fix High confidence

Upgrade to the specified fixed version for your product: 5.8.4 (most meeting clients), 5.0.1 (Chrome OS), 5.8.3 (Zoom Rooms), 5.7.6.1922 (Android SDK), or respective latest stable releases

  1. 1. Identify the specific Zoom product and current version installed from the list of affected products
  2. 2. For Zoom Client for Meetings (Windows/macOS/Linux/iOS/Android): upgrade to version 5.8.4 or later
  3. 3. For Zoom Client for Meetings for Blackberry (Android/iOS): upgrade to version 5.8.1 or later
  4. 4. For Zoom Client for Meetings for Intune (Android/iOS): upgrade to version 5.8.4 or later
  5. 5. For Zoom Client for Meetings for Chrome OS: upgrade to version 5.0.1 or later
  6. 6. For Zoom Rooms for Conference Rooms (Android/AndroidBali/macOS/Windows): upgrade to version 5.8.3 or later
  7. 7. For Controllers for Zoom Rooms (Android/iOS/Windows): upgrade to version 5.8.3 or later
  8. 8. For Virtual Desktop Infrastructure (VDI) clients: upgrade to version 5.8.4 or later
Caveat Upgrades typically maintain backward compatibility; ensure all meeting participants are using compatible versions to avoid interoperability issues

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,550. Get the upgrade done

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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-2021-34423 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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