CVE-2021-0876
📋 TL;DR
This CVE describes an integer overflow vulnerability in the PowerVR kernel driver for Android devices. It allows local attackers to gain kernel-level privileges without user interaction, potentially compromising the entire device. Affected systems include Android devices using PowerVR GPU hardware with vulnerable driver versions.
💻 Affected Systems
- Android devices with PowerVR GPU hardware
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent malware, access all user data, and bypass all security controls.
Likely Case
Local privilege escalation enabling unauthorized access to sensitive data and system resources.
If Mitigated
Limited impact if SELinux policies restrict kernel access and device is fully patched.
🎯 Exploit Status
Requires local access to device; kernel exploitation requires bypassing modern Android mitigations like KASLR, PAN, and CFI.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android security patch level April 2023 or later
Vendor Advisory: https://source.android.com/security/bulletin/2023-04-01
Restart Required: Yes
Instructions:
1. Check current Android security patch level in Settings > About phone > Android version. 2. If patch level is before April 2023, update device through Settings > System > System update. 3. Restart device after update completes.
🔧 Temporary Workarounds
Restrict kernel module loading
linuxPrevent loading of unauthorized kernel modules to reduce attack surface
echo 1 > /proc/sys/kernel/modules_disabled
🧯 If You Can't Patch
- Implement strict application allowlisting to prevent malicious apps from running
- Enable SELinux in enforcing mode and audit kernel access attempts
🔍 How to Verify
Check if Vulnerable:
Check Android security patch level: Settings > About phone > Android version > Security patch level. If date is before April 2023, device is vulnerable.Check Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify security patch level shows April 2023 or later after applying update.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- SELinux denials for PowerVR driver access
- Unexpected kernel module loads
Network Indicators:
- None (local-only vulnerability)
SIEM Query:
source="android_kernel" AND ("PowerVR" OR "PVRSRV") AND ("panic" OR "oops" OR "segfault")