● High · CVSS 8.6

How to Fix CVE-2026-3136: Incorrect authorization in Cloud Build

Q: What is the CVSS score for CVE-2026-3136?

8.6 (High). Vector: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/U:Clear`.

Q: Where is the official advisory for CVE-2026-3136?

The vendor advisory is at [https://docs.cloud.google.com/build/docs/release-notes#March_03_2026](https://docs.cloud.google.com/build/docs/release-notes#March_03_2026). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-3136.

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

CVE-2026-3136 is a incorrect authorization in Google Cloud Cloud Build. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	8.6 (High)
Actively exploited?	No public listing in CISA KEV
Affected	Cloud Build 0 to <1/26/2026
Fixed in	See vendor advisory
Type (CWE)	CWE-863 Incorrect Authorization (Permission Bypass)

What is CVE-2026-3136?

An improper authorization vulnerability in GitHub Trigger Comment Control in Google Cloud Build prior to 2026-1-26 allows a remote attacker to execute arbitrary code in the build environment.

This vulnerability was patched on 26 January 2026, and no customer action is needed. The CVSS base score is 8.6 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://docs.cloud.google.com/build/docs/release-notes#March_03_2026.

Am I affected?

Check the version of Cloud Build you are running and compare it against the Affected row above (Cloud Build 0 to <1/26/2026). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-3136

Upgrade Cloud Build 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 cloud-build
dpkg -s cloud-build | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update cloud-build
rpm -q cloud-build

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-3136 affecting Cloud Build
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-3136-fix-$(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"
    $pkg = Get-Package -Name "*Cloud Build*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "Cloud Build" --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 "Cloud Build"
    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-2026-3136 affecting Cloud Build
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-3136-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 cloud-build 2>/dev/null | grep -i ^Version || echo "cloud-build not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q cloud-build || echo "cloud-build not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-3136-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/cloud-build /etc/cloud-build.d /etc/cloud-build.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 cloud-build
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y cloud-build
elif command -v yum >/dev/null; then
    yum update -y cloud-build
elif command -v zypper >/dev/null; then
    zypper --non-interactive update cloud-build
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s cloud-build 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q cloud-build
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-2026-3136" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-3136"

Disable the affected service (Linux)


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

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

How to Fix CVE-2026-3259: CWE-209 Generation of error message containing sensitive information in BigQuery — CWE-209 Generation of error message containing sensitive information in BigQuery
How to Fix CVE-2026-5897: Chrome (Bundle Sibling) — Chrome (Bundle Sibling)
How to Fix CVE-2026-0907: Critical Vulnerability in Chrome , Critical Vulnerability in Chrome
How to Fix CVE-2026-8560: Path Traversal in Chrome , Path Traversal in Chrome
How to Fix CVE-2026-3940: Insufficient policy enforcement in Chrome , Insufficient policy enforcement in Chrome

Is CVE-2026-3136 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-2026-3136?

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-2026-3136?

8.6 (High). Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/U:Clear.

Where is the official advisory for CVE-2026-3136?

The vendor advisory is at https://docs.cloud.google.com/build/docs/release-notes#March_03_2026. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-3136.

References

Official vendor advisory: https://docs.cloud.google.com/build/docs/release-notes#March_03_2026
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3136
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.*