CVE-2021-1828
📋 TL;DR
This is a macOS kernel memory corruption vulnerability that allows an application to cause system crashes or write to kernel memory. It affects macOS Big Sur, Catalina, and Mojave systems before specific security updates. Attackers could potentially gain kernel-level privileges or cause denial of service.
💻 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
Kernel privilege escalation leading to full system compromise, persistence, and bypass of all security controls.
Likely Case
Local privilege escalation allowing an attacker to gain root access on the affected system.
If Mitigated
System crash or denial of service if exploitation attempts fail or are detected.
🎯 Exploit Status
Requires local access and ability to execute code. Memory corruption vulnerabilities typically require some exploitation expertise.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.3, Security Update 2021-002 Catalina, Security Update 2021-003 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212325
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available updates. 3. Restart when prompted. For managed environments, deploy updates via MDM or patch management tools.
🔧 Temporary Workarounds
No effective workarounds
allThis is a kernel-level vulnerability that cannot be mitigated without patching.
🧯 If You Can't Patch
- Restrict local user access to only trusted individuals
- Implement application allowlisting to prevent unauthorized applications from running
🔍 How to Verify
Check if Vulnerable:
Check macOS version: Big Sur < 11.3, Catalina without Security Update 2021-002, Mojave without Security Update 2021-003Check Version:
sw_versVerify Fix Applied:
Verify macOS version is Big Sur 11.3 or later, or that Catalina/Mojave have the specified security updates installed📡 Detection & Monitoring
Log Indicators:
- Kernel panics, unexpected system reboots, suspicious process spawning with elevated privileges
Network Indicators:
- None - this is a local exploit
SIEM Query:
macOS kernel panic events followed by suspicious privilege escalation attempts