How to Fix CVE-2026-27965: Os command injection in vitess

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

CVE-2026-27965 is a OS command injection in vitessio vitess. The fix is to apply the vendor patch noted below.

What is CVE-2026-27965?

Vitess is a database clustering system for horizontal scaling of MySQL. Prior to versions 23.0.3 and 22.0.4, anyone with read/write access to the backup storage location (e.g. an S3 bucket) can manipulate backup manifest files so that arbitrary code is later executed when that backup is restored. This can be used to provide that attacker with unintended/unauthorized access to the production deployment environment — allowing them to access information available in that environment as well as run any additional arbitrary commands there. Versions 23.0.3 and 22.0.4 contain a patch. Some workarounds are available. Those who intended to use an external decompressor then can always specify that decompressor command in the --external-decompressor flag value for vttablet and vtbackup. That then overrides any value specified in the manifest file. Those who did not intend to use an external decompressor, nor an internal one, can specify a value such as cat or tee in the --external-decompressor flag value for vttablet and vtbackup to ensure that a harmless command is always used. The CVSS base score is 8.4 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://github.com/vitessio/vitess/security/advisories/GHSA-8g8j-r87h-p36x.

Am I affected?

Check the version of vitess you are running and compare it against the Affected row above (vitess < 22.0.4; vitess >= 23.0.0, < 23.0.3). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:

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

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

How to fix CVE-2026-27965

Upgrade vitess 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 vitess
dpkg -s vitess | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux

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

SUSE / openSUSE

sudo zypper refresh
sudo zypper update vitess
rpm -q vitess

Node.js / npm

# Update the affected package in your project
npm install vitess@latest
npm ls vitess
npm audit fix

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-27965 affecting vitess
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27965-fix-$(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"
    $pkg = Get-Package -Name "*vitess*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "vitess" --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 "vitess"
    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-2026-27965 affecting vitess
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27965-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 vitess 2>/dev/null | grep -i ^Version || echo "vitess not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q vitess || echo "vitess not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27965-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/vitess /etc/vitess.d /etc/vitess.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 vitess
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y vitess
elif command -v yum >/dev/null; then
    yum update -y vitess
elif command -v zypper >/dev/null; then
    zypper --non-interactive update vitess
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s vitess 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q vitess
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-2026-27965" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27965"

Disable the affected service (Linux)

sudo systemctl stop vitess 2>/dev/null || true
sudo systemctl disable vitess 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 vitess 2>/dev/null | grep -i ^Version
rpm -q vitess 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 "*vitess*" | 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

Related fixes

Other vulnerabilities in the same area that are worth patching alongside this one:

• How to Fix CVE-2026-3904: CWE-366 Race condition within a thread in glibc — CWE-366 Race condition within a thread in glibc
• How to Fix CVE-2026-28195: Missing authorization in TeamCity , Missing authorization in TeamCity
• How to Fix CVE-2026-28428: Authentication bypass in Talishar , Authentication bypass in Talishar
• How to Fix CVE-2026-42875: Improper Authorization in external-secrets , Improper Authorization in external-secrets
• How to Fix CVE-2026-22458: Critical Vulnerability in Wanderland , Critical Vulnerability in Wanderland

Is CVE-2026-27965 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-2026-27965?

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-2026-27965?

8.4 (High). Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L.

Where is the official advisory for CVE-2026-27965?

The vendor advisory is at https://github.com/vitessio/vitess/security/advisories/GHSA-8g8j-r87h-p36x. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27965.

References

• Official vendor advisory: https://github.com/vitessio/vitess/security/advisories/GHSA-8g8j-r87h-p36x
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27965
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Additional reference: https://github.com/vitessio/vitess/issues/19459
• Additional reference: https://github.com/vitessio/vitess/pull/19460
• Additional reference: https://github.com/vitessio/vitess/commit/4c0173293907af9cb942a6683c465c3f1e9fdb5c

*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.*