CVE-2021-30683
📋 TL;DR
This is a use-after-free memory corruption vulnerability in macOS that allows malicious applications to execute arbitrary code. It affects macOS Big Sur, Catalina, and Mojave systems. Successful exploitation could lead to full system compromise and data theft.
💻 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 attacker gaining root privileges, data exfiltration, and persistent backdoor installation.
Likely Case
Local privilege escalation allowing malicious apps to bypass sandbox restrictions and access sensitive user data.
If Mitigated
Limited impact due to application sandboxing and system integrity protections if properly configured.
🎯 Exploit Status
Requires user to execute malicious application. Memory corruption vulnerabilities typically require specific conditions to exploit reliably.
🛠️ 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 when prompted. 4. Verify update installed successfully.
🔧 Temporary Workarounds
Application Execution Control
macosRestrict execution of untrusted applications using Gatekeeper and application whitelisting
sudo spctl --master-enable
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Implement strict application control policies to prevent execution of untrusted applications
- Enable full disk encryption and limit user privileges to reduce potential impact
🔍 How to Verify
Check if Vulnerable:
Check macOS version: sw_vers -productVersion. If version is: <11.4 (Big Sur), <10.15.7 (Catalina without 2021-003), or <10.14.6 (Mojave without 2021-004)Check Version:
sw_vers -productVersionVerify Fix Applied:
Verify macOS version meets patched requirements and check System Information > Software > Installations for security update presence📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes, memory access violations in system logs
- Unauthorized privilege escalation attempts
Network Indicators:
- Unusual outbound connections following local application execution
SIEM Query:
source="macos_system_logs" AND (event="kernel" OR event="sandbox") AND (message="access violation" OR message="memory corruption")