How to Fix CVE-2026-39842: Code injection in openremote

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

What is CVE-2026-39842?

OpenRemote is an open-source IoT platform. Versions 1.21.0 and below contain two interrelated expression injection vulnerabilities in the rules engine that allow arbitrary code execution on the server. The JavaScript rules engine executes user-supplied scripts via Nashorn's ScriptEngine.eval() without sandboxing, class filtering, or access restrictions, and the authorization check in RulesResourceImpl only restricts Groovy rules to superusers while leaving JavaScript rules unrestricted for any user with the write:rules role. Additionally, the Groovy rules engine has a GroovyDenyAllFilter security filter that is defined but never registered, as the registration code is commented out, rendering the SandboxTransformer ineffective for superuser-created Groovy rules.

Am I affected?

Run the version check that matches your platform:

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

Compare what you see against the Affected row above (openremote < 1.22.0). If your build sits inside that range, you are exposed and should patch.

How to fix CVE-2026-39842

The primary fix is to upgrade openremote to the patched build. Use the commands for your platform below; the patched version listed in the vendor advisory is: openremote 1.22.0.

Ubuntu / Debian

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

RHEL / CentOS / Rocky / AlmaLinux

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

SUSE / openSUSE

sudo zypper patch --category security
rpm -q openremote

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-39842 affecting openremote
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-39842-fix-$(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 openremote"
    $pkg = winget list --id "openremote" 2>$null
    Write-Host $pkg

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

    Write-Host "[3/4] Applying upgrade to openremote 1.22.0"
    winget upgrade --id "openremote" --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 "openremote"
    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-2026-39842 affecting openremote
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-39842-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 openremote 2>/dev/null | grep -i version || echo "openremote not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q openremote || echo "openremote not installed via rpm"
fi

echo "[2/4] Backing up configuration"
BACKUP="/root/backup-cve-2026-39842-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/openremote /etc/openremote.d /etc/openremote.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Applying upgrade (target: openremote 1.22.0)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y openremote
elif command -v dnf >/dev/null; then
    dnf upgrade --security -y openremote
elif command -v yum >/dev/null; then
    yum update -y openremote
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 openremote 2>/dev/null | grep -i version
elif command -v rpm >/dev/null; then
    rpm -q openremote
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 openremote
sudo systemctl disable openremote

How to verify the fix worked

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

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

Expected: the reported version is at or above openremote 1.22.0. 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.

Frequently asked questions

Related fixes

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

• How to Fix CVE-2026-2484: Critical Vulnerability in InfoSphere Information Server — Critical Vulnerability in InfoSphere Information Server
• How to Fix CVE-2026-0776: Critical Vulnerability in Client — Critical Vulnerability in Client
• How to Fix CVE-2026-22516: Critical Vulnerability in Wizor's , Critical Vulnerability in Wizor's
• How to Fix CVE-2026-22507: Deserialization RCE in Beelove , Deserialization RCE in Beelove
• How to Fix CVE-2026-33643: Critical Vulnerability in n/a , Critical Vulnerability in n/a

Is CVE-2026-39842 actually being exploited?

According to the data sources above, no public confirmation of in-the-wild exploitation at this time. 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?

10 (critical). 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://github.com/openremote/openremote/security/advisories/GHSA-7mqr-33rv-p3mp
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39842
• https://github.com/openremote/openremote/releases/tag/1.22.0

*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.*