● Medium · CVSS 4.8

How to Fix CVE-2026-3327: Cross-site scripting in Web Previews

Q: What is the CVSS score for CVE-2026-3327?

4.8 (Medium). Vector: `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`.

Q: Where is the official advisory for CVE-2026-3327?

The vendor advisory is at [https://github.com/datocms/plugins/commit/7965eebf0973cc5ebb18bc5ff9ce7ff19e89bb2e](https://github.com/datocms/plugins/commit/7965eebf0973cc5ebb18bc5ff9ce7ff19e89bb2e). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-3327.

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

CVE-2026-3327 is a cross-site scripting in DatoCMS Web Previews. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	4.8 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	Web Previews < 1.0.31
Fixed in	See vendor advisory
Type (CWE)	CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')

What is CVE-2026-3327?

Authenticated Iframe Injection in Dato CMS Web Previews plugin. This vulnerability permits a malicious authenticated user to circumvent the restriction enforced on the configured frontend URL, enabling the loading of arbitrary external resources or origins. This issue affects Web Previews < v1.0.31. The CVSS base score is 4.8 (Medium). The official advisory is at https://github.com/datocms/plugins/commit/7965eebf0973cc5ebb18bc5ff9ce7ff19e89bb2e.

Am I affected?

Check the version of Web Previews you are running and compare it against the Affected row above (Web Previews < 1.0.31). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-3327

Upgrade Web Previews to a patched build: See vendor advisory. 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 web-previews
dpkg -s web-previews | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update web-previews
rpm -q web-previews

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-3327 affecting Web Previews
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-3327-fix-$(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"
    $pkg = Get-Package -Name "*Web Previews*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "Web Previews" --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 "Web Previews"
    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-2026-3327 affecting Web Previews
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-3327-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 web-previews 2>/dev/null | grep -i ^Version || echo "web-previews not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q web-previews || echo "web-previews not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-3327-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/web-previews /etc/web-previews.d /etc/web-previews.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: See vendor advisory)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y web-previews
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y web-previews
elif command -v yum >/dev/null; then
    yum update -y web-previews
elif command -v zypper >/dev/null; then
    zypper --non-interactive update web-previews
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s web-previews 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q web-previews
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-2026-3327" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-3327"

Disable the affected service (Linux)


sudo systemctl stop web-previews 2>/dev/null || true
sudo systemctl disable web-previews 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 web-previews 2>/dev/null | grep -i ^Version
rpm -q web-previews 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 "*Web Previews*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above See vendor advisory. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

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

How to Fix CVE-2026-22052: Information disclosure via error message in ONTAP 9 — Information disclosure via error message in ONTAP 9
How to Fix CVE-2026-25060: Critical Vulnerability in OpenList — Critical Vulnerability in OpenList
How to Fix CVE-2026-25922: Authentication Bypass in authentik , Authentication Bypass in authentik
How to Fix CVE-2026-34828: listmonk: Active sessions remain valid after password reset and password change , listmonk: Active sessions remain valid after password reset and password change
How to Fix CVE-2026-34535: iccDEV (Bundle Sibling) , iccDEV (Bundle Sibling)

Is CVE-2026-3327 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-2026-3327?

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-2026-3327?

4.8 (Medium). Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.

Where is the official advisory for CVE-2026-3327?

The vendor advisory is at https://github.com/datocms/plugins/commit/7965eebf0973cc5ebb18bc5ff9ce7ff19e89bb2e. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-3327.

References

Official vendor advisory: https://github.com/datocms/plugins/commit/7965eebf0973cc5ebb18bc5ff9ce7ff19e89bb2e
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3327
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

*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.*