How to Fix CVE-2026-2994: Csrf in Concrete CMS

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

CVE-2026-2994 is a CSRF in Concrete CMS Concrete CMS. The fix is to upgrade to Concrete CMS 5.

What is CVE-2026-2994?

Concrete CMS below version 9.4.8 is subject to CSRF by a Rogue Administrator using the Anti-Spam Allowlist Group Configuration via group_id parameter which can leads to a security bypass since changes are saved prior to checking the CSRF token. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks z3rco for reporting The CVSS base score is 2.3 (Low). The official advisory is at https://github.com/concretecms/concretecms/pull/12826.

Am I affected?

Check the version of Concrete CMS you are running and compare it against the Affected row above (See vendor advisory). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:

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

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

How to fix CVE-2026-2994

Upgrade Concrete CMS to a patched build: Concrete CMS 5. 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 concrete-cms
dpkg -s concrete-cms | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux

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

SUSE / openSUSE

sudo zypper refresh
sudo zypper update concrete-cms
rpm -q concrete-cms

Node.js / npm

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

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-2994 affecting Concrete CMS
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-2994-fix-$(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"
    $pkg = Get-Package -Name "*Concrete CMS*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to Concrete CMS 5"
    winget upgrade --name "Concrete CMS" --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 "Concrete CMS"
    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-2026-2994 affecting Concrete CMS
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-2994-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 concrete-cms 2>/dev/null | grep -i ^Version || echo "concrete-cms not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q concrete-cms || echo "concrete-cms not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-2994-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/concrete-cms /etc/concrete-cms.d /etc/concrete-cms.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: Concrete CMS 5)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y concrete-cms
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y concrete-cms
elif command -v yum >/dev/null; then
    yum update -y concrete-cms
elif command -v zypper >/dev/null; then
    zypper --non-interactive update concrete-cms
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s concrete-cms 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q concrete-cms
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-2026-2994" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-2994"

Disable the affected service (Linux)

sudo systemctl stop concrete-cms 2>/dev/null || true
sudo systemctl disable concrete-cms 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 concrete-cms 2>/dev/null | grep -i ^Version
rpm -q concrete-cms 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 "*Concrete CMS*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above Concrete CMS 5. 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-2026-1496: Critical Vulnerability in Coverity — Critical Vulnerability in Coverity
• How to Fix CVE-2026-7592: SQL Injection in Courier Management System — SQL Injection in Courier Management System
• How to Fix CVE-2026-42303: Authentication Bypass in fides , Authentication Bypass in fides
• How to Fix CVE-2026-8084: Out-of-Bounds Read in gdal , Out-of-Bounds Read in gdal
• How to Fix CVE-2026-32045: Authentication Bypass in OpenClaw , Authentication Bypass in OpenClaw

Is CVE-2026-2994 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-2026-2994?

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-2026-2994?

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

Where is the official advisory for CVE-2026-2994?

The vendor advisory is at https://github.com/concretecms/concretecms/pull/12826. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-2994.

References

• Official vendor advisory: https://github.com/concretecms/concretecms/pull/12826
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2994
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Additional reference: https://documentation.concretecms.org/9-x/developers/introduction/version-history/948-release-notes

*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.*