CVE-2025-53490
📋 TL;DR
This CVE describes a cross-site scripting (XSS) vulnerability in the MediaWiki CampaignEvents extension that allows attackers to inject malicious scripts into web pages. The vulnerability affects MediaWiki installations using CampaignEvents extension versions 1.43.X before 1.43.2. Attackers could potentially steal user sessions, deface websites, or redirect users to malicious sites.
💻 Affected Systems
- Wikimedia Foundation MediaWiki - CampaignEvents Extension
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, take over MediaWiki instances, inject persistent malware into all users' browsers, or redirect users to phishing sites.
Likely Case
Attackers inject malicious JavaScript to steal user session cookies, perform actions on behalf of users, or deface campaign event pages.
If Mitigated
With proper input validation and output encoding, malicious scripts are neutralized before reaching users' browsers.
🎯 Exploit Status
XSS vulnerabilities typically require user interaction or specific conditions to trigger. The exact exploitation vector isn't specified in the references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.43.2
Vendor Advisory: https://phabricator.wikimedia.org/T395622
Restart Required: No
Instructions:
1. Update CampaignEvents extension to version 1.43.2 or later. 2. For MediaWiki: Navigate to extensions directory. 3. Update CampaignEvents: git pull or download new version. 4. Clear MediaWiki cache if needed.
🔧 Temporary Workarounds
Disable CampaignEvents Extension
allTemporarily disable the vulnerable extension until patching is possible
Edit LocalSettings.php and remove or comment out: wfLoadExtension('CampaignEvents');
Implement Content Security Policy
allAdd CSP headers to mitigate XSS impact
Add to web server config or MediaWiki: Header set Content-Security-Policy "default-src 'self'; script-src 'self'"
For Apache: Header set Content-Security-Policy "default-src 'self'; script-src 'self'"
For Nginx: add_header Content-Security-Policy "default-src 'self'; script-src 'self';";
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block XSS payloads
- Enable strict input validation and output encoding in application code
🔍 How to Verify
Check if Vulnerable:
Check CampaignEvents extension version in MediaWiki's Special:Version page or examine extension files for version 1.43.0 or 1.43.1Check Version:
grep -r 'version' /path/to/mediawiki/extensions/CampaignEvents/extension.json | grep -o '[0-9]\+\.[0-9]\+\.[0-9]\+'Verify Fix Applied:
Confirm CampaignEvents extension version is 1.43.2 or later via Special:Version page📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript payloads in request logs
- Multiple failed attempts with script tags in parameters
- Unexpected campaign event modifications
Network Indicators:
- HTTP requests containing script tags or JavaScript in campaign-related parameters
- Unusual outbound connections from MediaWiki server after campaign events
SIEM Query:
source="mediawiki_access.log" AND ("<script" OR "javascript:" OR "onload=" OR "onerror=") AND uri_path="/wiki/Special:CampaignEvents"