CVE-2021-30734
📋 TL;DR
This CVE describes memory corruption vulnerabilities in Apple's WebKit browser engine that could allow arbitrary code execution when processing malicious web content. Affected users include anyone running vulnerable versions of iOS, iPadOS, tvOS, macOS, or Safari who visits malicious websites. The vulnerabilities stem from improper memory handling (CWE-787) in the browser's rendering engine.
💻 Affected Systems
- iOS
- iPadOS
- tvOS
- Safari
- macOS Big Sur
- watchOS
📦 What is this software?
Ipados by Apple
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 →Safari by Apple
Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution, allowing attackers to install malware, steal data, or gain persistent access to the device.
Likely Case
Drive-by compromise where users visiting malicious websites get infected with malware or have sensitive data stolen without interaction.
If Mitigated
No impact if systems are fully patched and users avoid untrusted websites.
🎯 Exploit Status
Exploitation requires crafting malicious web content but no authentication or user interaction beyond visiting a website. Apple has not disclosed exploit details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 14.6, iPadOS 14.6, tvOS 14.6, Safari 14.1.1, macOS Big Sur 11.4, watchOS 7.5
Vendor Advisory: https://support.apple.com/en-us/HT212528
Restart Required: Yes
Instructions:
1. Open Settings app. 2. Go to General > Software Update. 3. Install available updates. 4. Restart device when prompted. For macOS: 1. Open System Preferences. 2. Click Software Update. 3. Install updates. 4. Restart computer.
🔧 Temporary Workarounds
Browser Restrictions
allRestrict use of Safari and other WebKit-based browsers to trusted websites only.
Content Filtering
allImplement web content filtering to block malicious websites and JavaScript from untrusted sources.
🧯 If You Can't Patch
- Isolate affected devices from internet access and restrict web browsing to internal resources only.
- Implement application whitelisting to prevent execution of unauthorized code.
🔍 How to Verify
Check if Vulnerable:
Check current OS/browser version against vulnerable versions listed in affected_systems.Check Version:
iOS/iPadOS: Settings > General > About > Version. macOS: Apple menu > About This Mac > macOS version. Safari: Safari menu > About Safari.Verify Fix Applied:
Verify OS/browser version matches or exceeds patched versions listed in fix_official.📡 Detection & Monitoring
Log Indicators:
- Unexpected browser crashes
- Memory access violations in system logs
- Unusual process creation from browser processes
Network Indicators:
- Connections to known malicious domains from browser processes
- Unusual outbound traffic patterns after web browsing
SIEM Query:
source="*system.log*" AND ("WebKit" OR "Safari") AND ("crash" OR "segmentation fault" OR "memory corruption")🔗 References
- https://support.apple.com/en-us/HT212528
- https://support.apple.com/en-us/HT212529
- https://support.apple.com/en-us/HT212532
- https://support.apple.com/en-us/HT212533
- https://support.apple.com/en-us/HT212534
- https://support.apple.com/en-us/HT212528
- https://support.apple.com/en-us/HT212529
- https://support.apple.com/en-us/HT212532
- https://support.apple.com/en-us/HT212533
- https://support.apple.com/en-us/HT212534
