CVE-2020-9926
📋 TL;DR
CVE-2020-9926 is a use-after-free vulnerability in Apple's XML processing that could allow attackers to crash applications or execute arbitrary code by processing malicious XML content. This affects multiple Apple operating systems and iCloud for Windows. Users running vulnerable versions of iOS, iPadOS, tvOS, watchOS, macOS, or iCloud for Windows are at risk.
💻 Affected Systems
- iOS
- iPadOS
- tvOS
- watchOS
- iCloud for Windows
- macOS
📦 What is this software?
Icloud by Apple
Ipados by Apple
Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with system-level privileges, potentially leading to complete device compromise, data theft, or persistent backdoor installation.
Likely Case
Application crashes (denial of service) when processing malicious XML, with potential for limited code execution in some scenarios.
If Mitigated
No impact if systems are fully patched or if XML processing from untrusted sources is blocked.
🎯 Exploit Status
Exploitation requires crafting malicious XML that triggers the use-after-free condition. No public exploit code was available at disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 13.6, iPadOS 13.6, tvOS 13.4.8, watchOS 6.2.8, iCloud for Windows 7.20, macOS Catalina 10.15.6, Security Update 2020-004 Mojave, Security Update 2020-004 High Sierra
Vendor Advisory: https://support.apple.com/en-us/HT211288
Restart Required: Yes
Instructions:
1. Go to Settings > General > Software Update on iOS/iPadOS. 2. Install available updates. 3. For macOS, go to System Preferences > Software Update. 4. For iCloud for Windows, update through Microsoft Store or Apple Software Update. 5. Restart devices after installation.
🔧 Temporary Workarounds
Block Untrusted XML Sources
allPrevent processing of XML from untrusted sources through web filtering, email filtering, or application controls.
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable devices from untrusted networks.
- Deploy application control solutions to restrict XML processing from untrusted applications.
🔍 How to Verify
Check if Vulnerable:
Check system version against affected versions list. On iOS/iPadOS: Settings > General > About > Version. On macOS: Apple menu > About This Mac.Check Version:
iOS/iPadOS: Settings > General > About. macOS: sw_vers. Windows: iCloud > About iCloud.Verify Fix Applied:
Verify system version matches or exceeds patched versions listed in the fix information.📡 Detection & Monitoring
Log Indicators:
- Application crashes related to XML parsing
- Unexpected process termination in system logs
Network Indicators:
- Unusual XML payloads in network traffic
- Suspicious file downloads with XML content
SIEM Query:
source="*system.log*" AND "terminated" AND ("XML" OR "libxml")🔗 References
- https://support.apple.com/en-us/HT211288
- https://support.apple.com/en-us/HT211289
- https://support.apple.com/en-us/HT211290
- https://support.apple.com/en-us/HT211291
- https://support.apple.com/en-us/HT211295
- https://support.apple.com/en-us/HT211288
- https://support.apple.com/en-us/HT211289
- https://support.apple.com/en-us/HT211290
- https://support.apple.com/en-us/HT211291
- https://support.apple.com/en-us/HT211295
