CVE-2021-30899
📋 TL;DR
This CVE describes a race condition vulnerability in macOS that allows a malicious application to execute arbitrary code with kernel privileges. It affects macOS Catalina, Big Sur, and Monterey before specific security updates. Attackers could gain complete control over affected systems.
💻 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 persistence, data theft, and backdoor installation.
Likely Case
Local privilege escalation allowing malicious applications to bypass security controls and access sensitive data.
If Mitigated
Limited impact with proper application sandboxing and user privilege separation in place.
🎯 Exploit Status
Requires race condition exploitation which can be challenging but feasible for skilled attackers. Needs local application execution.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Monterey 12.0.1, Security Update 2021-007 Catalina, macOS Big Sur 11.6.1
Vendor Advisory: https://support.apple.com/en-us/HT212869
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart your Mac when prompted.
🔧 Temporary Workarounds
Application Restriction
macosRestrict installation and execution of untrusted applications
sudo spctl --master-enable
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Implement strict application control policies to prevent untrusted application execution
- Use standard user accounts instead of admin accounts for daily use to limit impact
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running Catalina, Big Sur, or Monterey without the specified security updates, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version matches patched versions: Monterey 12.0.1+, Big Sur 11.6.1+, or Catalina with Security Update 2021-007.📡 Detection & Monitoring
Log Indicators:
- Unexpected kernel extensions loading
- Privilege escalation attempts in system logs
- Unauthorized process execution with elevated privileges
Network Indicators:
- None - local exploitation only
SIEM Query:
source="macos_system_logs" AND (event="kernel_extension_load" OR event="privilege_escalation")