CVE-2020-9893 – CVE-2020-9893 is a use-after-free vulnerability... (How to Fix)

Q: What is the severity of CVE-2020-9893?

CVE-2020-9893 has a CVSS score of 8.8 (HIGH). CVE-2020-9893 is a use-after-free vulnerability in Apple's memory management that could allow a remote attacker to crash applications or execute arbitrary code. This affects multiple Apple operating systems and applications including iOS, iPadOS, tvOS, watchOS, Safari, iTunes, and iCloud for Windows. Users running affected versions are vulnerable to exploitation.

📋 TL;DR

CVE-2020-9893 is a use-after-free vulnerability in Apple's memory management that could allow a remote attacker to crash applications or execute arbitrary code. This affects multiple Apple operating systems and applications including iOS, iPadOS, tvOS, watchOS, Safari, iTunes, and iCloud for Windows. Users running affected versions are vulnerable to exploitation.

💻 Affected Systems

Products:

iOS
iPadOS
tvOS
watchOS
Safari
iTunes for Windows
iCloud for Windows

Versions: Versions prior to iOS 13.6, iPadOS 13.6, tvOS 13.4.8, watchOS 6.2.8, Safari 13.1.2, iTunes 12.10.8, iCloud for Windows 11.3/7.20

Operating Systems: iOS, iPadOS, tvOS, watchOS, Windows

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations of affected products are vulnerable. Exploitation typically requires user interaction (visiting malicious website).

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or persistent backdoor installation.

🟠

Likely Case

Application crashes (denial of service) or limited code execution in sandboxed contexts.

🟢

If Mitigated

No impact if systems are fully patched or isolated from untrusted content.

🌐 Internet-Facing: HIGH - Remote exploitation possible via web content or network services.

🏢 Internal Only: MEDIUM - Requires user interaction or internal network access for exploitation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Use-after-free vulnerabilities require precise memory manipulation but are commonly exploited. No public exploit code was identified at disclosure.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: iOS 13.6, iPadOS 13.6, tvOS 13.4.8, watchOS 6.2.8, Safari 13.1.2, iTunes 12.10.8, iCloud for Windows 11.3/7.20

Vendor Advisory: https://support.apple.com/HT211288

Restart Required: Yes

Instructions:

1. Update iOS/iPadOS via Settings > General > Software Update. 2. Update macOS Safari via App Store updates. 3. Update Windows applications via Apple Software Update or download from Apple website. 4. Restart devices after installation.

🔧 Temporary Workarounds

Disable JavaScript in Safari

all

Temporarily reduces attack surface by disabling JavaScript execution in web content.

Safari > Preferences > Security > uncheck 'Enable JavaScript'

Network Segmentation

all

Isolate vulnerable devices from untrusted networks and internet access.

🧯 If You Can't Patch

Implement application whitelisting to prevent unauthorized code execution
Deploy network filtering to block malicious web content and restrict device internet access

🔍 How to Verify

Check if Vulnerable:

Check current version against patched versions listed in Apple advisories.

Check Version:

iOS/iPadOS: Settings > General > About > Version. macOS Safari: Safari > About Safari. Windows: Help > About in iTunes/iCloud.

Verify Fix Applied:

Confirm device/application version matches or exceeds patched versions.

📡 Detection & Monitoring

Log Indicators:

Application crashes (especially Safari/web processes)
Unexpected process termination
Memory access violation logs

Network Indicators:

Connections to suspicious domains serving web content
Unusual outbound traffic from Apple devices

SIEM Query:

source="apple-devices" AND (event_type="crash" OR error_code="EXC_BAD_ACCESS")

📊 Metadata

CVE ID: CVE-2020-9893

CVSS v3 Score: 8.8 (HIGH)

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

CWE: CWE-416

Published: October 16, 2020

Last Updated: November 21, 2024

🔗 References

https://support.apple.com/HT211288 Vendor Advisory
https://support.apple.com/HT211290 Vendor Advisory
https://support.apple.com/HT211291 Vendor Advisory
https://support.apple.com/HT211292 Vendor Advisory
https://support.apple.com/HT211293 Vendor Advisory
https://support.apple.com/HT211294 Vendor Advisory
https://support.apple.com/HT211295 Vendor Advisory
https://support.apple.com/HT211288 Vendor Advisory
https://support.apple.com/HT211290 Vendor Advisory
https://support.apple.com/HT211291 Vendor Advisory
https://support.apple.com/HT211292 Vendor Advisory
https://support.apple.com/HT211293 Vendor Advisory
https://support.apple.com/HT211294 Vendor Advisory
https://support.apple.com/HT211295 Vendor Advisory

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🔗 Related Vulnerabilities

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