CVE-2021-34424
📋 TL;DR
This vulnerability in Zoom clients and servers allows attackers to read arbitrary memory contents, potentially exposing sensitive information like session tokens, passwords, or encryption keys. It affects Zoom's desktop clients, mobile apps, meeting SDKs, VDI plugins, and on-premise components across all major operating systems. The memory exposure could lead to information disclosure that facilitates further attacks.
💻 Affected Systems
- Zoom Client for Meetings
- Zoom Client for Meetings for Blackberry
- Zoom Client for Meetings for Intune
- Zoom Client for Meetings for Chrome OS
- Zoom Rooms for Conference Room
- Controllers for Zoom Rooms
- Zoom VDI Windows Meeting Client
- Zoom VDI Azure Virtual Desktop Plugins
- Zoom VDI Citrix Plugins
- Zoom VDI VMware Plugins
- Zoom Meeting SDK
- Zoom Video SDK
- Zoom on-premise Meeting Connector
- Zoom on-premise Meeting Connector MMR
- Zoom on-premise Recording Connector
- Zoom on-premise Virtual Room Connector
- Zoom on-premise Virtual Room Connector Load Balancer
- Zoom Hybrid Zproxy
- Zoom Hybrid MMR
📦 What is this software?
Zoom On Premise Meeting Connector Controller by Zoom
View all CVEs affecting Zoom On Premise Meeting Connector Controller →
Zoom On Premise Meeting Connector Mmr by Zoom
View all CVEs affecting Zoom On Premise Meeting Connector Mmr →
Zoom On Premise Recording Connector by Zoom
View all CVEs affecting Zoom On Premise Recording Connector →
⚠️ Risk & Real-World Impact
Worst Case
Attackers could extract authentication tokens, encryption keys, or sensitive user data from memory, leading to account compromise, meeting hijacking, or data breaches.
Likely Case
Information leakage that could reveal session information, partial credentials, or system details that aid in reconnaissance for further attacks.
If Mitigated
Limited exposure of non-sensitive memory regions with minimal impact if proper network segmentation and access controls are implemented.
🎯 Exploit Status
Proof-of-concept code is publicly available, making exploitation straightforward for attackers with network access to vulnerable systems
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Zoom Client 5.8.4+, various other component-specific versions as listed in description
Vendor Advisory: https://explore.zoom.us/en/trust/security/security-bulletin
Restart Required: Yes
Instructions:
1. Identify all Zoom installations in your environment. 2. Update Zoom Client for Meetings to version 5.8.4 or later. 3. Update Zoom Rooms to version 5.8.3 or later. 4. Update all other affected components to their respective patched versions. 5. Restart systems after updates. 6. Verify updates completed successfully.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to Zoom services to trusted networks only
Disable Unnecessary Features
allDisable Zoom features not required for business operations to reduce attack surface
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure to trusted networks only
- Monitor for unusual memory access patterns or information leakage in network traffic
🔍 How to Verify
Check if Vulnerable:
Check Zoom client version in application settings or via command line: On Windows: 'zoom.exe --version', On macOS: '/Applications/zoom.us.app/Contents/Info.plist' or 'defaults read /Applications/zoom.us.app/Contents/Info.plist CFBundleShortVersionString', On Linux: Check package version via package managerCheck Version:
Windows: zoom.exe --version, macOS: defaults read /Applications/zoom.us.app/Contents/Info.plist CFBundleShortVersionString, Linux: dpkg -l | grep zoom or rpm -qa | grep zoomVerify Fix Applied:
Confirm version is at or above: Zoom Client 5.8.4, Zoom Rooms 5.8.3, and other component-specific patched versions📡 Detection & Monitoring
Log Indicators:
- Unusual memory access patterns
- Multiple failed memory read attempts
- Unexpected process memory dumps
Network Indicators:
- Unusual traffic to Zoom services from untrusted sources
- Patterns suggesting memory scraping
SIEM Query:
source="zoom*" AND (event_type="memory_access" OR event_type="process_dump")