How to Fix CVE-2020-0041: Improper input validation in Android

WARNING: This vulnerability is on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03). Federal civilian agencies must remediate by 2022-05-03. Treat it as active exploitation, not theoretical.

What is CVE-2020-0041?

In binder_transaction of binder.c, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-145988638References: Upstream kernel

Am I affected?

Run the version check that matches your platform:

# Linux
dpkg -s android 2>/dev/null | grep -i version
rpm -q android 2>/dev/null
android --version 2>/dev/null

# Android: Settings -> About phone -> Android version / Security patch level

Compare what you see against the Affected row above (Android Android kernel). If your build sits inside that range, you are exposed and should patch.

How to fix CVE-2020-0041

The primary fix is to upgrade Android to the patched build. Use the commands for your platform below; the patched version listed in the vendor advisory is: See vendor advisory.

Ubuntu / Debian

sudo apt-get update
sudo apt-get install --only-upgrade android
android --version 2>/dev/null || dpkg -s android | grep -i version

RHEL / CentOS / Rocky / AlmaLinux

sudo dnf upgrade --security android -y
rpm -q android

SUSE / openSUSE

sudo zypper patch --category security
rpm -q android

Android

Open Settings -> System -> System update -> Check for update on the device, then install the security patch issued by the vendor (OEM or Google). On supported Pixel devices:

# Vendor advisory: https://source.android.com/security/bulletin/2020-03-01
# From a workstation with adb + the OTA package
adb sideload <android-patched-ota>.zip

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2020-0041 affecting Android
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2020-0041-fix-$(Get-Date -Format yyyyMMdd-HHmmss).log"
New-Item -ItemType Directory -Force (Split-Path $LogPath) | Out-Null
Start-Transcript -Path $LogPath -Append

try {
    Write-Host "[1/4] Detecting installed version of Android"
    $pkg = winget list --id "Android" 2>$null
    Write-Host $pkg

    Write-Host "[2/4] Backing up configuration"
    $backup = "C:\Backup\Android-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\Android" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Applying upgrade to latest"
    winget upgrade --id "Android" --silent --accept-source-agreements --accept-package-agreements
    # Fallback: Windows Update for OS-level fixes
    if ($LASTEXITCODE -ne 0) {
        Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck -ErrorAction SilentlyContinue
        Import-Module PSWindowsUpdate
        Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -IgnoreReboot
    }

    Write-Host "[4/4] Verifying patched build"
    winget list --id "Android"
    Write-Host "Fix applied. Reboot if prompted."
    exit 0
} catch {
    Write-Error "Patch failed: $_"
    exit 1
} finally {
    Stop-Transcript
}

Complete Bash remediation script (Linux)

#!/usr/bin/env bash
# Fix script for CVE-2020-0041 affecting Android
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2020-0041-fix-$(date +%Y%m%d-%H%M%S).log"
exec > >(tee -a "$LOG") 2>&1

echo "[1/4] Detecting installed version"
if command -v dpkg >/dev/null; then
    dpkg -s android 2>/dev/null | grep -i version || echo "android not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q android || echo "android not installed via rpm"
fi

echo "[2/4] Backing up configuration"
BACKUP="/root/backup-cve-2020-0041-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/android /etc/android.d /etc/android.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Applying upgrade (target: latest)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y android
elif command -v dnf >/dev/null; then
    dnf upgrade --security -y android
elif command -v yum >/dev/null; then
    yum update -y android
elif command -v zypper >/dev/null; then
    zypper --non-interactive patch --category security
fi

echo "[4/4] Verifying patched build"
if command -v dpkg >/dev/null; then
    dpkg -s android 2>/dev/null | grep -i version
elif command -v rpm >/dev/null; then
    rpm -q android
fi
echo "Done. Restart any running daemons that loaded the old library."

If you can't patch immediately

If you cannot apply the patched version today, restrict exposure with one of the following runnable controls. None replace the patch.

Network restriction (Linux, nftables)

# Block inbound traffic to the affected service from untrusted networks
sudo nft add table inet filter
sudo nft 'add chain inet filter input { type filter hook input priority 0 ; }'
sudo nft 'add rule inet filter input tcp dport {443, 80} ip saddr != 10.0.0.0/8 drop'
sudo nft list ruleset

Service-level fallback

# If the affected feature is optional, stop the service until the patch is applied
sudo systemctl stop android
sudo systemctl disable android

How to verify the fix worked

# Linux
android --version 2>/dev/null || dpkg -s android | grep -i version
rpm -q android 2>/dev/null || true

# Windows
winget list | findstr /I "android"
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above the patched build documented in the advisory. Restart any services that loaded the old library (systemctl restart <service> on Linux, restart the Windows service or reboot when prompted). For network appliances, run show version on the device and confirm the build matches the patched release.

Is CVE-2020-0041 actually being exploited?

According to the data sources above, yes, CISA has it listed as actively exploited. Either way, the fix is the same: apply the vendor patch.

Do I need to reboot after patching?

For OS or kernel updates, yes. For most userland packages a systemctl restart <service> is enough. Any process that loaded the old shared library keeps using it until restarted, so when in doubt, reboot.

What is the CVSS score?

7.8 (high). Refer to the vendor advisory for the exact vector string.

Where is the official advisory?

See the References section at the bottom of this page; the vendor's URL is the authoritative source for affected builds and patched versions.

References

• Official vendor advisory: https://source.android.com/security/bulletin/2020-03-01
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-0041
• CISA KEV catalog entry: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-0041

Written by Sai Kiran Pandrala on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.

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