CVE-2021-30726
📋 TL;DR
This macOS kernel vulnerability allows malicious applications to write beyond allocated memory boundaries, potentially executing arbitrary code with kernel privileges. It affects macOS Big Sur, Catalina, and Mojave systems. Attackers could gain complete system control through specially crafted applications.
💻 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
Complete system compromise with kernel-level privileges, allowing installation of persistent malware, data theft, and system manipulation.
Likely Case
Malicious application gains kernel privileges to bypass security controls, install backdoors, or access sensitive system resources.
If Mitigated
Limited impact if systems are patched, application sandboxing is enforced, and only trusted applications are installed.
🎯 Exploit Status
Exploitation requires user interaction to install/run malicious application. No public exploit code available at disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.4, Security Update 2021-003 Catalina, Security Update 2021-004 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212529
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available updates. 3. Restart system when prompted.
🔧 Temporary Workarounds
Application Restriction
allRestrict installation and execution of untrusted applications
sudo spctl --master-enable
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Restrict user privileges and application installation rights
- Implement application allowlisting to prevent untrusted applications from running
🔍 How to Verify
Check if Vulnerable:
Check macOS version: sw_vers -productVersion. Compare against affected versions.Check Version:
sw_vers -productVersionVerify Fix Applied:
Verify macOS version is 11.4 or higher for Big Sur, or check Security Update installation date.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected application crashes with memory access errors
- Console.app entries showing out-of-bounds memory access
Network Indicators:
- Unusual outbound connections from kernel processes
- Suspicious network activity following application installation
SIEM Query:
source="macos" AND (event_type="kernel_panic" OR message="*out-of-bounds*" OR message="*memory corruption*")