CVE-2021-30933 – This macOS kernel vulnerability allows maliciou... (How to Fix)

Q: What is the severity of CVE-2021-30933?

CVE-2021-30933 has a CVSS score of 7.0 (HIGH). This macOS kernel vulnerability allows malicious applications to exploit a race condition to execute arbitrary code with kernel privileges. It affects macOS Big Sur and Monterey systems before specific security updates. Attackers could gain complete system control.

📋 TL;DR

This macOS kernel vulnerability allows malicious applications to exploit a race condition to execute arbitrary code with kernel privileges. It affects macOS Big Sur and Monterey systems before specific security updates. Attackers could gain complete system control.

💻 Affected Systems

Products:

macOS

Versions: macOS Big Sur before 11.6, macOS Monterey before 12.0.1

Operating Systems: macOS

Default Config Vulnerable: ⚠️ Yes

Notes: Requires user to install/run malicious application; not remotely exploitable without user interaction.

📦 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

Full system compromise with kernel-level persistence, data theft, and complete control over affected Mac systems.

🟠

Likely Case

Malicious applications bypassing security controls to install malware, keyloggers, or ransomware with kernel privileges.

🟢

If Mitigated

Limited impact with proper application sandboxing and security controls preventing malicious app installation.

🌐 Internet-Facing: LOW

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires race condition exploitation in kernel state handling; needs malicious application execution.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: macOS Big Sur 11.6, macOS Monterey 12.0.1

Vendor Advisory: https://support.apple.com/en-us/HT212804

Restart Required: Yes

Instructions:

1. Open System Preferences > Software Update. 2. Install available macOS updates. 3. Restart when prompted.

🔧 Temporary Workarounds

Application Restriction

all

Restrict installation of untrusted applications via Gatekeeper and System Preferences

sudo spctl --master-enable
sudo spctl --enable

🧯 If You Can't Patch

Restrict user privileges and application installation capabilities
Implement application allowlisting to prevent unauthorized software execution

🔍 How to Verify

Check if Vulnerable:

Check macOS version: if running Big Sur < 11.6 or Monterey < 12.0.1, system is vulnerable.

Check Version:

sw_vers

Verify Fix Applied:

Verify macOS version is 11.6 or higher for Big Sur, or 12.0.1 or higher for Monterey.

📡 Detection & Monitoring

Log Indicators:

Kernel panic logs
Unexpected kernel extensions loading
Unauthorized privilege escalation attempts

Network Indicators:

Unusual outbound connections from kernel processes

SIEM Query:

source="macos" AND (event="kernel_panic" OR process="kernel_task" AND action="privilege_escalation")

📊 Metadata

CVE ID: CVE-2021-30933

CVSS v3 Score: 7.0 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-362

Published: August 24, 2021

Last Updated: November 21, 2024

🔗 References

📤 Share & Export

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🔗 Related Vulnerabilities

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