CVE-2025-25062
📋 TL;DR
A stored cross-site scripting (XSS) vulnerability in Backdrop CMS allows attackers to inject malicious JavaScript into content that executes when administrators edit that content. This affects Backdrop CMS installations using the CKEditor 5 module. Attackers need content creation privileges and administrators must edit (not just view) the malicious content.
💻 Affected Systems
- Backdrop CMS
📦 What is this software?
Backdrop Cms by Backdropcms
Backdrop Cms by Backdropcms
⚠️ Risk & Real-World Impact
Worst Case
Administrator account compromise leading to full site takeover, data theft, or malware distribution to site visitors.
Likely Case
Session hijacking of administrator accounts, defacement of administrative interfaces, or limited data exfiltration.
If Mitigated
No impact if administrators don't edit malicious content or if proper input validation is implemented.
🎯 Exploit Status
Exploitation requires authenticated user with content creation permissions. Public technical details available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.28.5 or 1.29.3
Vendor Advisory: https://backdropcms.org/security/backdrop-sa-core-2025-001
Restart Required: No
Instructions:
1. Backup your site. 2. Update Backdrop CMS to version 1.28.5 or 1.29.3 via the update manager or manual download. 3. Clear all caches. 4. Verify CKEditor 5 module is updated.
🔧 Temporary Workarounds
Disable CKEditor 5 module
allTemporarily disable the vulnerable CKEditor 5 module until patching is possible
Navigate to /admin/modules, uncheck CKEditor 5, save configuration
Restrict content creation permissions
allLimit who can create/edit content to trusted users only
Navigate to /admin/people/permissions, review and restrict 'Create content' permissions
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to block inline JavaScript execution
- Enable XSS filtering in web application firewall or reverse proxy
🔍 How to Verify
Check if Vulnerable:
Check Backdrop CMS version in /admin/reports/status. If using CKEditor 5 and version is 1.28.0-1.28.4 or 1.29.0-1.29.2, you are vulnerable.Check Version:
Visit /admin/reports/status in your Backdrop CMS installationVerify Fix Applied:
After update, verify version shows 1.28.5 or 1.29.3 in /admin/reports/status. Test content editing functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual content creation patterns
- Administrator account editing suspicious content
- JavaScript errors in admin logs
Network Indicators:
- Unusual POST requests to content creation endpoints
- Suspicious JavaScript payloads in HTTP traffic
SIEM Query:
source="web_logs" AND (uri_path="/node/add" OR uri_path="/comment/reply") AND (http_user_agent CONTAINS "script" OR http_body CONTAINS "<script>")