● Critical · CVSS 9.7

How to Fix CVE-2026-28495: CWE-352: Cross-Site Request Forgery (CSRF) in GetSimpleCMS-CE

Q: Is CVE-2026-28495 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-2026-28495?

CVSS rates it 9.7 (Critical). Use that score to set your patch priority next to the other items in your queue.

Q: Do I have to take GetSimpleCMS-CE 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-2026-28495 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-2026-26320: Critical Vulnerability in openclaw — Critical Vulnerability in openclaw
How to Fix CVE-2026-33935: Critical Vulnerability in MyTube — Critical Vulnerability in MyTube
How to Fix CVE-2026-40864: Cross-Site Request Forgery in jupyterhub , Cross-Site Request Forgery in jupyterhub
How to Fix CVE-2026-4836: SQL Injection in Accounting System , SQL Injection in Accounting System
How to Fix CVE-2026-42296: Incorrect Authorization in argo-workflows , Incorrect Authorization in argo-workflows

*By Sai Kiran Pandrala*

⚡ At a glance


Severity	CVSS 9.7, Critical
Actively exploited?	No
Affected	GetSimpleCMS-CE (<= 3.3.22)
Fixed in	See vendor advisory
Type (CWE)	CWE-352: Cross-Site Request Forgery (CSRF)

What is CVE-2026-28495?

GetSimple CMS is a content management system. The massiveAdmin plugin (v6.0.3) bundled with GetSimpleCMS-CE v3.3.22 allows an authenticated administrator to overwrite the gsconfig.php configuration file with arbitrary PHP code via the gsconfig editor module. The form lacks CSRF protection, enabling a remote unauthenticated attacker to exploit this via Cross-Site Request Forgery against a logged-in admin, achieving Remote Code Execution (RCE) on the web server.

In practical terms, a successful attacker gets remote code execution on the affected system. 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 GetSimpleCMS-CE 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 getsimplecms-ce   # Debian/Ubuntu
rpm -qa | grep -i getsimplecms-ce   # RHEL/CentOS/Rocky

How to fix CVE-2026-28495

The primary fix is to upgrade to the patched build listed in the Fixed in row above (See vendor advisory). Pick the platform that matches your install and run the commands below.

Linux (Ubuntu / Debian)


# Vendor advisory: https://github.com/GetSimpleCMS-CE/GetSimpleCMS-CE/security/advisories/GHSA-92wv-q2jp-qg88
sudo apt-get update
sudo apt-get install --only-upgrade getsimplecms-ce
# Confirm the installed version meets or exceeds <patched-version>
dpkg -s getsimplecms-ce | grep ^Version

Linux (RHEL / CentOS / Rocky)


sudo dnf upgrade --security getsimplecms-ce -y
rpm -q getsimplecms-ce

Windows (PowerShell, admin)


# Vendor advisory: https://github.com/GetSimpleCMS-CE/GetSimpleCMS-CE/security/advisories/GHSA-92wv-q2jp-qg88
# Try winget first
winget upgrade --id 'Getsimplecms-ce.GetSimpleCMS-CE' --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\GetSimpleCMSCE-<patched-version>.msi" -ArgumentList '/qn /norestart' -Wait

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


# Vendor advisory: https://github.com/GetSimpleCMS-CE/GetSimpleCMS-CE/security/advisories/GHSA-92wv-q2jp-qg88
# Run as Administrator
$ErrorActionPreference = 'Stop'
$log = "$env:ProgramData\GetSimpleCMSCE-Patch-CVE-2026-28495.log"
function Write-Log($msg) { "$(Get-Date -Format s)  $msg" | Tee-Object -FilePath $log -Append }

Write-Log "Starting CVE-2026-28495 remediation for Getsimplecms-ce GetSimpleCMS-CE"

# 1. Detect: replace the path/version probe with one valid for your install
$installed = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*GetSimpleCMS-CE*' } |
    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]'<patched-version>') {
    Write-Log "Already at fixed version $installed; no action needed."
    return
}

# 2. Backup configuration to a timestamped folder
$backup = "$env:ProgramData\GetSimpleCMSCE-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\Getsimplecms-ce\GetSimpleCMS-CE"
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\GetSimpleCMSCE-<patched-version>.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 { $_.Name -like '*GetSimpleCMS-CE*' } |
    Select-Object -First 1 -ExpandProperty Version)
if ([version]$verify -ge [version]'<patched-version>') {
    Write-Log "SUCCESS: now at $verify (>= <patched-version>)"
} else {
    Write-Log "FAILURE: still at $verify after install"
    exit 1
}

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


# Vendor advisory: https://github.com/GetSimpleCMS-CE/GetSimpleCMS-CE/security/advisories/GHSA-92wv-q2jp-qg88
#!/usr/bin/env bash
set -euo pipefail
LOG=/var/log/getsimplecms-ce-patch-cve-2026-28495.log
log()  { echo "$(date -Iseconds)  $*" | tee -a "$LOG"; }

log "Starting CVE-2026-28495 remediation for Getsimplecms-ce GetSimpleCMS-CE"

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

# 2. Backup config
BACKUP=/var/backups/getsimplecms-ce-$(date +%Y%m%d-%H%M)
mkdir -p "$BACKUP"
for d in /etc/getsimplecms-ce /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 getsimplecms-ce
else
    sudo dnf upgrade --security -y getsimplecms-ce
fi

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

# Optionally compare against <patched-version> 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.

Rate-limit and log the affected endpoint at the reverse proxy


limit_req_zone $binary_remote_addr zone=admin:10m rate=10r/m;
location /<vulnerable-path> {
    limit_req zone=admin burst=5 nodelay;
    access_log /var/log/nginx/admin-access.log combined;
    proxy_pass http://backend;
}

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 "getsimplecms-ce"   # Debian/Ubuntu
rpm -qa | grep -i "getsimplecms-ce"   # RHEL/CentOS/Rocky

Expected output: the package version should meet or exceed the patched build.

Then re-run any vulnerability scanner you used previously and confirm the finding for CVE-2026-28495 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-2026-28495 being actively exploited?