How to Fix CVE-2026-22711: Stored XSS through system messages in WikiLove
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*By Sai Kiran Pandrala*
Last verified: 2026-05-25
| Severity | CVSS 6.9, Medium |
|---|---|
| Actively exploited? | No |
| Affected | the Wikimedia Foundation Mediawiki - Wikilove Extension (0 < 1.43) |
| Fixed in | 1.43 |
| Type (CWE) | CWE-87: Improper neutralization of alternate XSS syntax |
CVE-2026-22711 is a stored xss through system messages in wikilove in the Wikimedia Foundation Mediawiki - Wikilove Extension. The fix is to upgrade to 1.43 and apply the runnable commands below.
What is CVE-2026-22711?
Improper neutralization of alternate XSS syntax vulnerability in The Wikimedia Foundation Mediawiki - Wikilove Extension allows Cross-Site Scripting (XSS).The issue has been remediated on the master branch, and in the release branches for MediaWiki versions 1.43, 1.44, and 1.45.
In practical terms, a successful attacker gets execution of attacker-controlled JavaScript in a victim's browser. 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 are affected if you run the Wikimedia Foundation Mediawiki - Wikilove Extension at a version listed in the Affected row above. Probe your installed build with the commands below.
# Confirm the installed version via your package manager
dpkg -l | grep -i mediawiki # Debian/Ubuntu
rpm -qa | grep -i mediawiki # RHEL/CentOS/Rocky
How to fix CVE-2026-22711
The primary fix is to upgrade to the patched build listed in the Fixed in row above (1.43). 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 mediawiki---wikilove-extension
# Confirm the installed version meets or exceeds 1.43
dpkg -s mediawiki---wikilove-extension | grep ^Version
Linux (RHEL / CentOS / Rocky)
sudo dnf upgrade --security mediawiki---wikilove-extension -y
rpm -q mediawiki---wikilove-extension
Windows (PowerShell, admin)
winget upgrade --id 'theWikimediaFoundation.MediawikiWikiloveExtension' --silent --accept-source-agreements --accept-package-agreements
# If winget doesn't know the product, download the patched installer from the vendor and:
Start-Process -FilePath "$env:TEMP\MediawikiWikiloveExtension-1.43.msi" -ArgumentList '/qn /norestart' -Wait
PowerShell script (Windows): detect, back up, upgrade, verify, log
# Run as Administrator
$ErrorActionPreference = 'Stop'
$log = "$env:ProgramData\MediawikiWikiloveExtension-Patch-CVE-2026-22711.log"
function Write-Log($msg) { "$(Get-Date -Format s) $msg" | Tee-Object -FilePath $log -Append }
Write-Log "Starting CVE-2026-22711 remediation for the Wikimedia Foundation Mediawiki - Wikilove Extension"
# 1. Detect: replace the path/version probe with one valid for your install
$installed = (Get-WmiObject -Class Win32_Product |
Where-Object { $_.Name -like '*Mediawiki*' } |
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]'1.43') {
Write-Log "Already at fixed version $installed; no action needed."
return
}
# 2. Backup configuration to a timestamped folder
$backup = "$env:ProgramData\MediawikiWikiloveExtension-Backup-$(Get-Date -Format yyyyMMdd-HHmm)"
New-Item -ItemType Directory -Path $backup -Force | Out-Null
$src = "$env:ProgramFiles\the Wikimedia Foundation\Mediawiki - Wikilove Extension"
if (Test-Path $src) { Copy-Item -Path $src -Destination $backup -Recurse -Force }
Write-Log "Backed up config to $backup"
# 3. Apply the patched installer
$installer = "$env:TEMP\MediawikiWikiloveExtension-1.43.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 { $_.Name -like '*Mediawiki*' } |
Select-Object -First 1 -ExpandProperty Version)
if ([version]$verify -ge [version]'1.43') {
Write-Log "SUCCESS: now at $verify (>= 1.43)"
} else {
Write-Log "FAILURE: still at $verify after install"
exit 1
}
Bash script (Linux): detect, back up, upgrade, verify, log
#!/usr/bin/env bash
set -euo pipefail
LOG=/var/log/mediawiki---wikilove-extension-patch-cve-2026-22711.log
log() { echo "$(date -Iseconds) $*" | tee -a "$LOG"; }
log "Starting CVE-2026-22711 remediation for the Wikimedia Foundation Mediawiki - Wikilove Extension"
# 1. Detect installed version (works for deb and rpm packages)
if command -v dpkg >/dev/null && dpkg -s mediawiki---wikilove-extension >/dev/null 2>&1; then
CURRENT=$(dpkg-query -W -f='${Version}' mediawiki---wikilove-extension)
PKG_MGR=apt
elif command -v rpm >/dev/null && rpm -q mediawiki---wikilove-extension >/dev/null 2>&1; then
CURRENT=$(rpm -q --queryformat '%{VERSION}' mediawiki---wikilove-extension)
PKG_MGR=dnf
else
log "mediawiki---wikilove-extension not installed via apt or rpm; check your package manager or vendor instructions."
exit 0
fi
log "Detected: mediawiki---wikilove-extension=$CURRENT (manager=$PKG_MGR)"
# 2. Backup config
BACKUP=/var/backups/mediawiki---wikilove-extension-$(date +%Y%m%d-%H%M)
mkdir -p "$BACKUP"
for d in /etc/mediawiki---wikilove-extension /etc/${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 mediawiki---wikilove-extension
else
sudo dnf upgrade --security -y mediawiki---wikilove-extension
fi
# 4. Verify
if [ "$PKG_MGR" = apt ]; then
NEW=$(dpkg-query -W -f='${Version}' mediawiki---wikilove-extension)
else
NEW=$(rpm -q --queryformat '%{VERSION}' mediawiki---wikilove-extension)
fi
log "After upgrade: $NEW"
log "Done. Compare $NEW against 1.43 and restart the affected service if needed."
If you cannot patch immediately
These are runnable hardening commands. They reduce blast radius but they are not a replacement for the vendor patch.
Tighten Content-Security-Policy and cookie flags
add_header Content-Security-Policy "default-src 'self'; script-src 'self'" always;
add_header X-Frame-Options DENY always;
add_header X-Content-Type-Options nosniff always;
How to verify the fix worked
Run the version probe again and confirm the running build matches the Fixed in row above.
dpkg -l | grep -i "mediawiki" # Debian/Ubuntu
rpm -qa | grep -i "mediawiki" # RHEL/CentOS/Rocky
Expected output: the package version should meet or exceed 1.43.
Re-run any vulnerability scanner you used previously and confirm the finding for CVE-2026-22711 has cleared. Sweep your logs for 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-2026-22711 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.
How severe is CVE-2026-22711?
CVSS rates it 6.9 (Medium). Use that score to set your patch priority alongside the other items in your queue.
Do I have to take Mediawiki - Wikilove Extension 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.
What if my vulnerability scanner still flags CVE-2026-22711 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.
References
- Official vendor advisory: https://phabricator.wikimedia.org/T416502
- NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-22711
- CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- Additional reference: https://gerrit.wikimedia.org/r/q/Iab86209478a044504f5a6aea0d8c3d14f21c48b3
*Written by Sai Kiran Pandrala. Last verified 2026-05-25. Sourced from the official vendor advisory, the NVD record, and the CISA KEV listing. Always confirm against the vendor advisory before applying changes in production.*