CVE-2021-30922
📋 TL;DR
This CVE describes multiple out-of-bounds write vulnerabilities in macOS that could allow a malicious application to execute arbitrary code with kernel privileges. Affected systems are macOS Big Sur versions prior to 11.6.1. This is a local privilege escalation vulnerability requiring user interaction to run a malicious application.
💻 Affected Systems
- macOS
📦 What is this software?
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with kernel-level access, allowing attackers to install persistent malware, steal sensitive data, or disable security controls.
Likely Case
Local privilege escalation where a user-level application gains kernel privileges to bypass security restrictions or install additional malware.
If Mitigated
Limited impact if proper application sandboxing and least privilege principles are enforced, though kernel access still represents significant risk.
🎯 Exploit Status
Exploitation requires user interaction to execute malicious code. The vulnerability involves out-of-bounds write issues that need to be carefully crafted for successful exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.6.1
Vendor Advisory: https://support.apple.com/en-us/HT212872
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Click 'Update Now' if macOS Big Sur 11.6.1 is available. 3. Follow on-screen instructions to download and install. 4. Restart your Mac when prompted.
🔧 Temporary Workarounds
Application Restriction
allRestrict execution of untrusted applications using Gatekeeper and only install software from trusted sources
sudo spctl --master-enable
sudo spctl --enable --label "Mac App Store"
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Implement strict application control policies to prevent execution of untrusted applications
- Enforce least privilege principles and monitor for suspicious kernel-level activity
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running macOS Big Sur version earlier than 11.6.1, the system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is 11.6.1 or later using 'sw_vers' command.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected kernel extensions loading
- Suspicious process spawning with elevated privileges
Network Indicators:
- Not applicable - local privilege escalation
SIEM Query:
source="macos" AND (event_type="kernel_panic" OR process_name CONTAINS "kernel" AND privilege_change="escalated")