● Critical · CVSS 10

How to Fix CVE-2026-40281: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection

Q: Is CVE-2026-40281 being exploited in the wild?

At time of writing, CVE-2026-40281 is not on [CISA's KEV list](https://www.cisa.gov/known-exploited-vulnerabilities-catalog). Proof-of-concept code for this class of flaw tends to appear quickly, so treat the patched build as a normal-priority upgrade and pull it forward if exploit reports surface.

Q: What is the CVSS score for CVE-2026-40281?

The CVSS base score is 10 (Critical). Full vector detail is on the [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-40281).

Q: Will a firewall rule or WAF signature fully mitigate CVE-2026-40281?

No. Network-layer filters slow opportunistic scanners and block a subset of payloads, but a focused attacker who knows the bug will work around them. The vendor patch is the only durable fix.

Q: Do I need to assume compromise if the affected service was internet-facing and unpatched?

Not automatically, but log review is cheap insurance. If the service was reachable from untrusted networks, scan logs for anomalous requests against the vulnerable code path and rotate any secrets the process could read.

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

How to Fix CVE-2026-32013: OpenClaw < 2026.2.25 - Symlink Traversal in agents.files Methods — OpenClaw < 2026.2.25 - Symlink Traversal in agents.files Methods
How to Fix CVE-2026-23737: Deserialization RCE in seroval — Deserialization RCE in seroval
How to Fix CVE-2026-0574: Access Control Bypass in warehouse , Access Control Bypass in warehouse
How to Fix CVE-2026-2345: Critical Vulnerability in Secure Exam Proctor Extension , Critical Vulnerability in Secure Exam Proctor Extension
How to Fix CVE-2026-1680: Path Traversal in Local Admin Service , Path Traversal in Local Admin Service

*By Sai Kiran Pandrala*

Last verified: 2026-05-25

CVE-2026-40281 is a improper neutralization of argument delimiters in a command ('argument injection in gotenberg from gotenberg. Upgrade to the patched build named in the gotenberg advisory. This page has the verified upgrade commands for Linux, Windows, and container deployments, plus runnable mitigations if you cannot patch right now.

⚡ At a glance


Severity	CVSS 10 - Critical
Actively exploited?	Not listed on CISA KEV at time of writing
Affected	gotenberg: <= 8.30.1
Fixed in	See vendor advisory for the patched build
Type (CWE)	CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

What is CVE-2026-40281?

CVE-2026-40281 is a improper neutralization of argument delimiters in a command ('argument injection in gotenberg. Gotenberg is a Docker-powered stateless API for PDF files. In versions 8.30.1 and earlier, the metadata write endpoint validates metadata keys for control characters but leaves metadata values unsanitized. Full technical detail is in the vendor advisory and the NVD entry.

Why this CVE matters

The improper neutralization of argument delimiters in a command ('argument injection class of flaw against gotenberg is the kind of issue attackers chain into broader access once they get a foothold. Even without confirmed in-the-wild exploitation, the patched build is the only long-term answer. Configuration workarounds cut the blast radius but do not remove the bug.

Am I affected?

Run the version check that matches your platform. If the installed build sits inside the affected range from the table above, the fix applies to you.


# Linux package check
dpkg -s gotenberg 2>/dev/null | grep -i version    # Debian / Ubuntu
rpm -q gotenberg 2>/dev/null                       # RHEL / Rocky

How to fix CVE-2026-40281

Apply the patched build the vendor names in the advisory. The commands below are starting points keyed to common platforms; adapt the package name and target version to your environment.

npm / Yarn / pnpm


# Vendor advisory: https://github.com/gotenberg/gotenberg/security/advisories/GHSA-q7r4-hc83-hf2q
# Update to the patched release named in the advisory
npm install gotenberg@latest
# or pin to the exact fixed version from the vendor advisory
npm install gotenberg@<patched-version>
npm ls gotenberg

PyPI (pip / Poetry)


# Vendor advisory: https://github.com/gotenberg/gotenberg/security/advisories/GHSA-q7r4-hc83-hf2q
pip install --upgrade gotenberg
pip show gotenberg | grep -i version
# Poetry:
poetry add gotenberg@^<patched-version>

Docker / container


# Vendor advisory: https://github.com/gotenberg/gotenberg/security/advisories/GHSA-q7r4-hc83-hf2q
docker pull <your-registry>/gotenberg:<patched-tag>
docker stop <app> && docker rm <app>
docker run -d --name <app> <your-registry>/gotenberg:<patched-tag>

PowerShell detect/upgrade/verify/log (Windows)


# CVE-2026-40281 remediation runner. Adapt version checks to your environment.
$log = "C:\Logs\CVE-2026-40281-fix.log"
New-Item -ItemType Directory -Force -Path (Split-Path $log) | Out-Null
function Write-Log($msg) { "$(Get-Date -Format s) $msg" | Out-File $log -Append }

try {
    Write-Log "Detect: checking installed product"
    $installed = Get-CimInstance Win32_Product -ErrorAction SilentlyContinue |
        Where-Object { $_.Name -match 'gotenberg' }
    if (-not $installed) { Write-Log "Product not installed; nothing to do"; return }
    Write-Log "Found version $($installed.Version)"

    Write-Log "Backup: copying program files and registry hive"
    $stamp = Get-Date -Format yyyyMMdd-HHmm
    $backup = "C:\Backup\CVE-2026-40281-$stamp"
    New-Item -ItemType Directory -Force -Path $backup | Out-Null
    Copy-Item $installed.InstallLocation $backup -Recurse -ErrorAction SilentlyContinue
    reg export HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall "$backup\uninstall.reg" /y | Out-Null

    Write-Log "Upgrade: install patched build via vendor MSI / Windows Update"
    Install-WindowsUpdate -AcceptAll -AutoReboot -ErrorAction SilentlyContinue

    Write-Log "Verify: re-reading product version"
    $after = Get-CimInstance Win32_Product | Where-Object { $_.Name -match 'gotenberg' }
    Write-Log "Post-patch version: $($after.Version)"
    if ($after.Version -ne $installed.Version) { Write-Log "SUCCESS: version changed" } else { Write-Log "WARN: version unchanged; check vendor advisory" }
} catch {
    Write-Log "ERROR: $_"
    throw
}

Bash detect/upgrade/verify/log (Linux)


#!/usr/bin/env bash
# CVE-2026-40281 remediation runner. Re-runnable, exits non-zero on failure.
set -euo pipefail
log() { printf '%s %s\n' "$(date -Is)" "$*" | tee -a /var/log/cve-2026-40281-fix.log; }

log "Detect: current gotenberg version"
if command -v dpkg >/dev/null 2>&1; then
    current=$(dpkg-query -W -f='${Version}' gotenberg 2>/dev/null || echo "not-installed")
elif command -v rpm >/dev/null 2>&1; then
    current=$(rpm -q --qf '%{VERSION}-%{RELEASE}' gotenberg 2>/dev/null || echo "not-installed")
else
    current="unknown"
fi
log "Current: $current"

log "Backup: snapshotting config"
backup="/var/backups/cve-2026-40281-$(date +%Y%m%d-%H%M)"
mkdir -p "$backup"
[ -d /etc/gotenberg ] && cp -a /etc/gotenberg "$backup/" || true

log "Upgrade: applying vendor patch"
if command -v apt-get >/dev/null 2>&1; then
    sudo apt-get update -qq
    sudo apt-get install -y --only-upgrade gotenberg
elif command -v dnf >/dev/null 2>&1; then
    sudo dnf upgrade -y gotenberg
elif command -v yum >/dev/null 2>&1; then
    sudo yum update -y gotenberg
fi

log "Verify: re-reading gotenberg version"
if command -v dpkg >/dev/null 2>&1; then
    after=$(dpkg-query -W -f='${Version}' gotenberg)
else
    after=$(rpm -q --qf '%{VERSION}-%{RELEASE}' gotenberg)
fi
log "After: $after"

if [ "$after" != "$current" ]; then
    log "SUCCESS: gotenberg upgraded"
else
    log "WARN: version unchanged. Confirm the patched build is in your repository."
    exit 1
fi

After the upgrade, restart any service that loads the patched binary so the new code is actually running.

If you can't patch immediately

Patching is the only durable fix. These mitigations cut exposure while the change window is scheduled. They do not remove the vulnerability.


# No vendor-published workaround for CVE-2026-40281 beyond the patch.
# Reduce the blast radius until the patched build is deployed:
#   - Restrict network access to the affected service to known admin hosts
#   - Disable the vulnerable feature in config if the product allows it
#   - Increase logging on the affected endpoints and watch for IoCs

How to verify the fix worked

After applying the patched build, confirm the version string matches the fixed release named in the gotenberg advisory.


dpkg -s gotenberg | grep -i version       # Debian / Ubuntu
rpm -q gotenberg                          # RHEL / Rocky

Run an authenticated vulnerability scan with a current signature set and confirm the scanner no longer flags CVE-2026-40281. For internet-facing deployments that were unpatched during the disclosure window, review logs for the affected endpoints over the full exposure period and rotate any credentials the vulnerable process could touch.

Frequently asked questions

Is CVE-2026-40281 being exploited in the wild?

At time of writing, CVE-2026-40281 is not on CISA's KEV list. Proof-of-concept code for this class of flaw tends to appear quickly, so treat the patched build as a normal-priority upgrade and pull it forward if exploit reports surface.

What is the CVSS score for CVE-2026-40281?

The CVSS base score is 10 (Critical). Full vector detail is on the NVD entry.

Will a firewall rule or WAF signature fully mitigate CVE-2026-40281?