CVE-2021-30719
📋 TL;DR
This macOS vulnerability allows local users to read kernel memory or cause system crashes through an out-of-bounds read. It affects macOS systems prior to Big Sur 11.4 and Catalina Security Update 2021-003. Attackers with local access can exploit this to potentially access sensitive kernel data.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation leading to full system compromise, kernel memory disclosure exposing sensitive system information, or persistent denial of service through system crashes.
Likely Case
Local user causing system crashes or reading limited kernel memory, potentially leading to information disclosure about system state or processes.
If Mitigated
Minimal impact if systems are patched; unpatched systems with strict local access controls face reduced risk.
🎯 Exploit Status
Requires local user access and knowledge of the vulnerability. Apple has not disclosed technical details, making exploitation more difficult.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.4 or macOS Catalina Security Update 2021-003
Vendor Advisory: https://support.apple.com/en-us/HT212529
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install macOS Big Sur 11.4 update or Security Update 2021-003 for Catalina. 3. Restart the system when prompted.
🔧 Temporary Workarounds
Restrict local user access
allLimit local user accounts to trusted personnel only and implement strict access controls.
🧯 If You Can't Patch
- Implement strict local access controls and limit user privileges
- Monitor for unusual system crashes or kernel-related errors
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running macOS Big Sur earlier than 11.4 or macOS Catalina without Security Update 2021-003, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is 11.4 or higher for Big Sur, or check that Security Update 2021-003 is installed for Catalina.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected system restarts
- Kernel memory access errors in system logs
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
Search for kernel panic events or unexpected system restarts in macOS logs