● Low · CVSS 2.3

How to Fix CVE-2026-3237: Low-Privilege User Can Modify Global Signing Key Settings

Q: Is CVE-2026-3237 being actively exploited?

Not at the time of writing. It is not listed in CISA's Known Exploited Vulnerabilities catalog. That status can change, so monitor the vendor advisory and the KEV catalog if the system is exposed.

Q: How severe is CVE-2026-3237?

CVSS rates it 2.3 (Low). Use that score to set your patch priority next to the other items in your queue.

Q: Do I have to take Octopus Server offline to apply the patch?

It depends on the deployment. High-availability or clustered installs can usually patch one node at a time with no full outage. Standalone installs typically need a short restart. Always follow the vendor's documented upgrade steps.

Q: What if my vulnerability scanner still flags CVE-2026-3237 after I patch?

Re-run the scan after a service restart, then confirm the scanner's plugin set is up to date. Some scanners detect by banner version only and lag the official fix metadata by a release.

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

How to Fix CVE-2026-4503: CWE-639 Authorization Bypass Through User-Controlled Key in Langflow Desktop — CWE-639 Authorization Bypass Through User-Controlled Key in Langflow Desktop
How to Fix CVE-2026-22044: SQL Injection in glpi — SQL Injection in glpi
How to Fix CVE-2026-8421: Cross-Site Request Forgery in Concrete CMS , Cross-Site Request Forgery in Concrete CMS
How to Fix CVE-2026-32938: Path Traversal in siyuan , Path Traversal in siyuan
How to Fix CVE-2026-26209: Critical Vulnerability in cbor2 , Critical Vulnerability in cbor2

*By Sai Kiran Pandrala*

⚡ At a glance


Severity	CVSS 2.3, Low
Actively exploited?	No
Affected	Octopus Deploy Octopus Server (2023.0.0 < 2025.3.14731, 2025.4.0 < 2025.4.10359, 2026.1.0 < 2026.1.5571)
Fixed in	2025.3.14731, 2025.4.10359, 2026.1.5571
Type (CWE)	Low-Privilege User Can Modify Global Signing Key Settings

What is CVE-2026-3237?

In affected versions of Octopus Server it was possible for a low privileged user to manipulate an API request to change the signing key expiration and revocation time frames via an API endpoint that had incorrect permission validation. It was not possible to expose the signing keys using this vulnerability.

In practical terms, a successful attacker gets compromise of the affected component as described in the vendor advisory. There is no confirmed in-the-wild exploitation listed in CISA's KEV catalog at the time of writing, but the CVSS rating still warrants prompt patching.

Am I affected?

You're affected if you run Octopus Deploy Octopus Server at any version in the Affected row above. Use these probes to find your installed build:


# Confirm the installed version via your package manager
dpkg -l | grep -i octopus   # Debian/Ubuntu
rpm -qa | grep -i octopus   # RHEL/CentOS/Rocky

How to fix CVE-2026-3237

The primary fix is to upgrade to the patched build listed in the Fixed in row above (2025.3.14731, 2025.4.10359, 2026.1.5571). Pick the platform that matches your install and run the commands below.

Linux (Ubuntu / Debian)


sudo apt-get update
sudo apt-get install --only-upgrade octopus-server
# Confirm the installed version meets or exceeds 2025.3.14731
dpkg -s octopus-server | grep ^Version

Linux (RHEL / CentOS / Rocky)


sudo dnf upgrade --security octopus-server -y
rpm -q octopus-server

Windows (PowerShell, admin)


# Try winget first
winget upgrade --id 'Octopus Deploy.Octopus Server' --silent --accept-source-agreements --accept-package-agreements
# If winget does not know the product, download the patched installer from the vendor and:
Start-Process -FilePath "$env:TEMP\OctopusServer-2025.3.14731.msi" -ArgumentList '/qn /norestart' -Wait

PowerShell script (Windows) - detect, back up, upgrade, verify, log


# Run as Administrator
$ErrorActionPreference = 'Stop'
$log = "$env:ProgramData\OctopusServer-Patch-CVE-2026-3237.log"
function Write-Log($msg) { "$(Get-Date -Format s)  $msg" | Tee-Object -FilePath $log -Append }

Write-Log "Starting CVE-2026-3237 remediation for Octopus Deploy Octopus Server"

# 1. Detect: replace the path/version probe with one valid for your install
$installed = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*Octopus*' } |
    Select-Object -First 1 -ExpandProperty Version)
Write-Log "Detected version: $installed"

if (-not $installed) {
    Write-Log "Product not installed on this host; nothing to do."
    return
}
if ([version]$installed -ge [version]'2025.3.14731') {
    Write-Log "Already at fixed version $installed; no action needed."
    return
}

# 2. Backup configuration to a timestamped folder
$backup = "$env:ProgramData\OctopusServer-Backup-$(Get-Date -Format yyyyMMdd-HHmm)"
New-Item -ItemType Directory -Path $backup -Force | Out-Null
# Adjust the source path to match your install
$src = "$env:ProgramFiles\Octopus Deploy\Octopus Server"
if (Test-Path $src) { Copy-Item -Path $src -Destination $backup -Recurse -Force }
Write-Log "Backed up config to $backup"

# 3. Apply the patched installer (place the verified file on a share or staging path)
$installer = "$env:TEMP\OctopusServer-2025.3.14731.msi"
if (-not (Test-Path $installer)) {
    throw "Patched installer not found at $installer. Stage it from your software repo first."
}
Start-Process msiexec.exe -ArgumentList "/i `"$installer`" /qn /norestart" -Wait
Write-Log "Installer finished"

# 4. Verify
$verify = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*Octopus*' } |
    Select-Object -First 1 -ExpandProperty Version)
if ([version]$verify -ge [version]'2025.3.14731') {
    Write-Log "SUCCESS: now at $verify (>= 2025.3.14731)"
} else {
    Write-Log "FAILURE: still at $verify after install"
    exit 1
}

Bash script (Linux) - detect, back up, upgrade, verify, log


#!/usr/bin/env bash
set -euo pipefail
LOG=/var/log/octopus-server-patch-cve-2026-3237.log
log()  { echo "$(date -Iseconds)  $*" | tee -a "$LOG"; }

log "Starting CVE-2026-3237 remediation for Octopus Deploy Octopus Server"

# 1. Detect installed version (works for deb and rpm packages)
if command -v dpkg >/dev/null && dpkg -s octopus-server >/dev/null 2>&1; then
    CURRENT=$(dpkg-query -W -f='${Version}' octopus-server)
    PKG_MGR=apt
elif command -v rpm >/dev/null && rpm -q octopus-server >/dev/null 2>&1; then
    CURRENT=$(rpm -q --queryformat '%{VERSION}' octopus-server)
    PKG_MGR=dnf
else
    log "octopus-server not installed via apt or rpm; check your package manager or vendor instructions."
    exit 0
fi
log "Detected: octopus-server=$CURRENT (manager=$PKG_MGR)"

# 2. Backup config
BACKUP=/var/backups/octopus-server-$(date +%Y%m%d-%H%M)
mkdir -p "$BACKUP"
for d in /etc/octopus-server /etc/${pkg%%-*} ; do
    [ -d "$d" ] && cp -a "$d" "$BACKUP/" && log "Backed up $d to $BACKUP"
done

# 3. Upgrade
if [ "$PKG_MGR" = apt ]; then
    sudo apt-get update -y
    sudo apt-get install --only-upgrade -y octopus-server
else
    sudo dnf upgrade --security -y octopus-server
fi

# 4. Verify
if [ "$PKG_MGR" = apt ]; then
    NEW=$(dpkg-query -W -f='${Version}' octopus-server)
else
    NEW=$(rpm -q --queryformat '%{VERSION}' octopus-server)
fi
log "After upgrade: $NEW"

# Optionally compare against 2025.3.14731 with dpkg --compare-versions or sort -V
log "Done. Restart the affected service if the package install did not."

If you can't patch immediately

These are runnable hardening commands. They reduce blast radius but they're not a replacement for the vendor patch.

No official vendor workaround is published for this CVE; patching is the only documented fix. The runnable hardening below is generic defense in depth, not a substitute for the patch.

Restrict the affected service to trusted networks (Linux):


# Vendor advisory: https://advisories.octopus.com/post/2026/sa2026-03
# Replace <port> with the affected service port and 10.0.0.0/24 with your admin subnet
sudo iptables -A INPUT -p tcp --dport <port> -s 10.0.0.0/24 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport <port> -j DROP

Windows Firewall equivalent:


# Vendor advisory: https://advisories.octopus.com/post/2026/sa2026-03
New-NetFirewallRule -DisplayName 'Allow affected service from admin subnet' \
    -Direction Inbound -Action Allow -Protocol TCP -LocalPort <port> -RemoteAddress 10.0.0.0/24
New-NetFirewallRule -DisplayName 'Block affected service from everywhere else' \
    -Direction Inbound -Action Block -Protocol TCP -LocalPort <port>

How to verify the fix worked

Run the version probe again and confirm the running build matches the Fixed in row above.


# Confirm the running build matches the patched version listed by the vendor
# Example for Linux package installs:
dpkg -l | grep -i "octopus"   # Debian/Ubuntu
rpm -qa | grep -i "octopus"   # RHEL/CentOS/Rocky

Expected output: the package version should meet or exceed 2025.3.14731.

Then re-run any vulnerability scanner you used previously and confirm the finding for CVE-2026-3237 has cleared. Sweep your logs for the indicators of compromise listed in the vendor or CISA advisory, especially if the system was internet-reachable during the disclosure window.

Frequently asked questions

Is CVE-2026-3237 being actively exploited?