CVE-2020-27936
📋 TL;DR
CVE-2020-27936 is an out-of-bounds read vulnerability in macOS kernel memory that allows local users to read kernel memory or cause system crashes. This affects macOS Catalina, Mojave, and earlier Big Sur versions. Attackers with local access can potentially access sensitive kernel data.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ 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 (kernel panics) or reading limited kernel memory to gather system information for further attacks.
If Mitigated
Limited impact with proper access controls restricting local user privileges and timely patching preventing exploitation.
🎯 Exploit Status
Requires local user access and knowledge of kernel memory structures. No public exploit code available at disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212011
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart system when prompted. 4. Verify update installed via About This Mac > System Report.
🔧 Temporary Workarounds
Restrict Local User Access
allLimit local user accounts and privileges to reduce attack surface
🧯 If You Can't Patch
- Implement strict access controls to limit local user privileges
- Monitor system logs for kernel panic events and unusual local user activity
🔍 How to Verify
Check if Vulnerable:
Check macOS version via 'sw_vers' command or About This Mac > OverviewCheck Version:
sw_versVerify Fix Applied:
Verify macOS version is 11.1 or higher for Big Sur, or check Security Update installation in System Report📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs in /Library/Logs/DiagnosticReports
- System crash reports
- Unexpected system restarts
Network Indicators:
- No network indicators - local vulnerability only
SIEM Query:
source="macos" AND (event_type="kernel_panic" OR message="panic" OR message="system crash")