● High · CVSS 7.2

How to Fix CVE-2026-20416: Out-of-bounds write in MediaTek chipset

Q: What is the CVSS score for CVE-2026-20416?

7.2 (High). Vector: `CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`.

Q: Where is the official advisory for CVE-2026-20416?

The vendor advisory is at [https://corp.mediatek.com/product-security-bulletin/March-2026](https://corp.mediatek.com/product-security-bulletin/March-2026). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-20416.

By Sai Kiran Pandrala. Last verified: 2026-05-25.

CVE-2026-20416 is a out-of-bounds write in MediaTek, Inc. MediaTek chipset. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	7.2 (High)
Actively exploited?	No public listing in CISA KEV
Affected	MediaTek chipset MT6991; MediaTek chipset MT6993; MediaTek chipset MT8188; MediaTek chipset MT8678
Fixed in	See vendor advisory
Type (CWE)	CWE-787 Out-of-bounds Write

What is CVE-2026-20416?

In pcie, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege if a malicious actor has already obtained the System privilege. User interaction is not needed for exploitation. Patch ID: ALPS10315038 / ALPS10340155; Issue ID: MSV-5155. The CVSS base score is 7.2 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://corp.mediatek.com/product-security-bulletin/March-2026.

Am I affected?

Check the version of MediaTek chipset you are running and compare it against the Affected row above (MediaTek chipset MT6991; MediaTek chipset MT6993; MediaTek chipset MT8188; MediaTek chipset MT8678). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


# Linux package check
dpkg -s mediatek-chipset 2>/dev/null | grep -i ^Version
rpm -q mediatek-chipset 2>/dev/null
command -v mediatek-chipset >/dev/null && mediatek-chipset --version 2>/dev/null


# Windows (PowerShell)
Get-Package -Name "*MediaTek chipset*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "MediaTek chipset" 2>$null

How to fix CVE-2026-20416

Upgrade MediaTek chipset to a patched build: See vendor advisory. The vendor advisory is the source of truth for the exact fixed version.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade mediatek-chipset
dpkg -s mediatek-chipset | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


sudo dnf upgrade --refresh mediatek-chipset -y
# or for older releases:
sudo yum update mediatek-chipset -y
rpm -q mediatek-chipset

SUSE / openSUSE


sudo zypper refresh
sudo zypper update mediatek-chipset
rpm -q mediatek-chipset

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-20416 affecting MediaTek chipset
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-20416-fix-$(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] Detect installed version"
    $pkg = Get-Package -Name "*MediaTek chipset*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "MediaTek chipset" --silent --accept-source-agreements --accept-package-agreements
    if ($LASTEXITCODE -ne 0) {
        # Fallback: pull latest via OS update channel
        Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck -ErrorAction SilentlyContinue
        Import-Module PSWindowsUpdate
        Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -IgnoreReboot
    }

    Write-Host "[4/4] Verify the patched build"
    winget list --name "MediaTek chipset"
    Write-Host "Patch 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-2026-20416 affecting MediaTek chipset
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-20416-fix-$(date +%Y%m%d-%H%M%S).log"
exec > >(tee -a "$LOG") 2>&1

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

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-20416-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/mediatek-chipset /etc/mediatek-chipset.d /etc/mediatek-chipset.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: See vendor advisory)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y mediatek-chipset
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y mediatek-chipset
elif command -v yum >/dev/null; then
    yum update -y mediatek-chipset
elif command -v zypper >/dev/null; then
    zypper --non-interactive update mediatek-chipset
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s mediatek-chipset 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q mediatek-chipset
fi
echo "Done. Restart any service that loaded the old library."

If you can't patch immediately

Apply at least one of the following inline controls until you can deploy the patched build. None replace the upgrade.

Restrict exposure with nftables (Linux)


# Allow only trusted CIDR to reach the affected service ports
sudo nft add table inet filter 2>/dev/null || true
sudo nft 'add chain inet filter input { type filter hook input priority 0 ; }' 2>/dev/null || true
sudo nft 'add rule inet filter input tcp dport {80, 443} ip saddr != 10.0.0.0/8 drop'
sudo nft list ruleset

Block at the host firewall (Windows)


New-NetFirewallRule -DisplayName "Block-CVE-2026-20416" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-20416"

Disable the affected service (Linux)


sudo systemctl stop mediatek-chipset 2>/dev/null || true
sudo systemctl disable mediatek-chipset 2>/dev/null || true

If the vendor advisory lists an official workaround, prefer that wording verbatim. If no workaround is published, the only safe remediation is the patch.

How to verify the fix worked

After upgrading, confirm the installed version matches the patched build and that no old library is still loaded by a long-running process.


# Linux
dpkg -s mediatek-chipset 2>/dev/null | grep -i ^Version
rpm -q mediatek-chipset 2>/dev/null || true
# Pid map check for old library handles
sudo lsof +c0 2>/dev/null | grep -i "DEL.*lib" || true


# Windows
Get-Package -Name "*MediaTek chipset*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above See vendor advisory. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

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Is CVE-2026-20416 actively exploited?

There is no public confirmation of exploitation in the wild listed in CISA KEV at the time of this writing. Patch anyway. Public exploits commonly follow disclosure within weeks.

Do I need to reboot after patching CVE-2026-20416?

For kernel and OS-level updates, yes. For most userland packages a systemctl restart <service> is enough on Linux, and restarting the Windows service or app on Windows. Any process that loaded the old library keeps using it until restarted.

What is the CVSS score for CVE-2026-20416?

7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

Where is the official advisory for CVE-2026-20416?

The vendor advisory is at https://corp.mediatek.com/product-security-bulletin/March-2026. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-20416.

References

Official vendor advisory: https://corp.mediatek.com/product-security-bulletin/March-2026
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20416
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

*Written by Sai Kiran Pandrala. Assembled from the official vendor advisory, NVD record, and CISA KEV listing on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.*