CVE-2021-34423

Name: CVE-2021-34423
Creator: NVD / NIST
Published: 2021-11-24T17:15:07.757+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.21%

Last modified Jun 17, 2026

CVE-2021-34423 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 3.21% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.21%

86.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-120

Affected Software

Vendor	Product	Versions
Zoom	Meetings	< 5.8.3
Zoom	Meetings	< 5.8.4
Zoom	Meetings For Blackberry	< 5.8.1
Zoom	Meetings For Intune	< 5.8.4
Zoom	Meetings For Chrome Os	< 5.0.1
Zoom	Rooms For Conference Rooms	< 5.8.3
Zoom	Controllers For Zoom Rooms	< 5.8.3
Zoom	Virtual Desktop Infrastructure	< 5.8.4
Zoom	Android Meeting Sdk	< 5.7.6.1922
Zoom	Iphone Os Meeting Sdk	< 5.7.6.1082
Zoom	Macos Meeting Sdk	< 5.7.6.1340
Zoom	Windows Meeting Sdk	< 5.7.6.1081
Zoom	Android Video Sdk	< 1.1.2
Zoom	Iphone Os Video Sdk	< 1.1.2
Zoom	Macos Video Sdk	< 1.1.2
Zoom	Windows Video Sdk	< 1.1.2
Zoom	Hybrid Mmr	< 4.6.20211116.131
Zoom	Hybrid Zproxy	< 1.0.1058.20211116
Zoom	Zoom On-Premise Meeting Connector Controller	< 4.8.12.20211115
Zoom	Zoom On-Premise Meeting Connector Mmr	< 4.8.12.20211115
Zoom	Zoom On-Premise Recording Connector	< 5.1.0.65.20211116
Zoom	Zoom On-Premise Virtual Room Connector	< 4.4.7266.20211117
Zoom	Zoom On-Premise Virtual Room Connector Load Balancer	< 2.5.5692.20211117
Zoom	Vdi Azure Virtual Desktop	< 5.8.4.21112
Zoom	Vdi Citrix	< 5.8.4.21112
Zoom	Vdi Vmware	< 5.8.4.21112
Zoom	Vdi Windows Meeting Client	< 5.8.4

References

http://packetstormsecurity.com/files/165417/Zoom-Chat-Message-Processing-Buffer-Overflow.htmlThird Party Advisory, VDB Entry
https://explore.zoom.us/en/trust/security/security-bulletinVendor Advisory
http://packetstormsecurity.com/files/165417/Zoom-Chat-Message-Processing-Buffer-Overflow.htmlThird Party Advisory, VDB Entry
https://explore.zoom.us/en/trust/security/security-bulletinVendor Advisory

Timeline

Published: Nov 24, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-34423?

How severe is CVE-2021-34423?

CVE-2021-34423 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.21% probability of exploitation in the next 30 days.

How do I fix CVE-2021-34423?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-34423?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST