CVE-2021-0520
📋 TL;DR
This CVE describes a use-after-free vulnerability in Android's MemoryFileSystem due to a race condition. It allows local privilege escalation without requiring user interaction or additional execution privileges. Affected users are those running Android 10 or 11 without the June 2021 security patches.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
An attacker with local access could exploit this to gain root privileges, potentially compromising the entire device, accessing sensitive data, or installing persistent malware.
Likely Case
Local attackers could elevate privileges to gain unauthorized access to system resources, install malicious apps, or bypass security controls.
If Mitigated
With proper patching, the vulnerability is eliminated. On unpatched systems, Android's sandboxing and SELinux policies would limit the impact but not prevent exploitation.
🎯 Exploit Status
Exploitation requires local access and knowledge of the race condition timing. No public exploit code is known, but the vulnerability is documented in Android security bulletins.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Patch Level June 2021 or later
Vendor Advisory: https://source.android.com/security/bulletin/2021-06-01
Restart Required: Yes
Instructions:
1. Check current Android security patch level in Settings > About phone > Android version. 2. If patch level is before June 2021, install the latest Android security update via Settings > System > System update. 3. Restart the device after update installation.
🔧 Temporary Workarounds
No effective workarounds
allThis is a kernel-level vulnerability in Android's memory management system. No configuration changes or application-level workarounds can mitigate it.
🧯 If You Can't Patch
- Restrict physical access to vulnerable devices and implement strict app installation policies
- Monitor devices for unusual privilege escalation attempts using mobile device management (MDM) solutions
🔍 How to Verify
Check if Vulnerable:
Check Android security patch level: Settings > About phone > Android version > Security patch level. If date is before June 2021, device is vulnerable.Check Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify security patch level shows June 2021 or later after applying updates.📡 Detection & Monitoring
Log Indicators:
- Kernel crash logs related to memory corruption
- Unexpected privilege escalation in system logs
- SELinux denials for unauthorized system access
Network Indicators:
- No direct network indicators as this is a local exploit
SIEM Query:
No standard SIEM query available as detection would require kernel-level monitoring on individual devices