CVE-2021-0921
📋 TL;DR
This vulnerability in Android's Parcel serialization allows local privilege escalation without user interaction. An attacker could exploit improper input validation in ParsingPackageImpl to gain elevated privileges on affected devices. Only Android 11 devices are affected.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to execute arbitrary code with system privileges, access sensitive data, or install persistent malware.
Likely Case
Local attacker gains elevated privileges to access protected system resources or user data they shouldn't normally access.
If Mitigated
With proper patching, no impact as the vulnerability is fixed at the OS level.
🎯 Exploit Status
Exploitation requires understanding of Android Parcel serialization and creating a malicious app, but no user interaction or special permissions needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Patch Level 2021-11-01 or later
Vendor Advisory: https://source.android.com/security/bulletin/2021-11-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > Advanced > System update. 2. Install the November 2021 security patch or later. 3. Reboot device after installation.
🔧 Temporary Workarounds
No effective workarounds
allThis is a core Android framework vulnerability requiring OS-level patching.
🧯 If You Can't Patch
- Restrict physical access to devices and monitor for suspicious app installations
- Implement mobile device management (MDM) to control app installations and monitor device integrity
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If it shows Android 11, check Security patch level. If before November 2021, device is vulnerable.Check Version:
adb shell getprop ro.build.version.release && adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify Security patch level shows November 2021 or later in Settings > About phone > Android version > Security patch level.📡 Detection & Monitoring
Log Indicators:
- Unusual system service crashes
- Suspicious package parsing errors in logcat
- Unexpected privilege escalation attempts
Network Indicators:
- Not applicable - local exploit only
SIEM Query:
Not applicable for typical SIEM monitoring as this is a local device exploit