CVE-2026-27147
📋 TL;DR
GetSimple CMS is vulnerable to cross-site scripting (XSS) through SVG file uploads. Authenticated users can upload malicious SVG files containing JavaScript that executes when viewed in a browser. All GetSimple CMS installations with file upload functionality enabled are affected.
💻 Affected Systems
- GetSimple CMS
📦 What is this software?
Getsimple Cms by Getsimple Ce
⚠️ Risk & Real-World Impact
Worst Case
An authenticated attacker could upload malicious SVG files that execute JavaScript in administrators' browsers, potentially leading to session hijacking, account takeover, or complete compromise of the CMS administration panel.
Likely Case
Authenticated users with upload privileges can inject malicious scripts that execute when other users view the uploaded SVG files, potentially stealing session cookies or performing actions on behalf of victims.
If Mitigated
With proper input validation and content security policies, the impact is limited to potential data leakage from users who view malicious files.
🎯 Exploit Status
Exploitation requires authenticated access but is trivial once authenticated. SVG files with embedded JavaScript can be easily crafted.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: https://github.com/GetSimpleCMS-CE/GetSimpleCMS-CE/security/advisories/GHSA-5gmq-hrcx-6w45
Restart Required: No
Instructions:
No official patch available. Monitor vendor advisory for updates.
🔧 Temporary Workarounds
Disable SVG uploads
allModify GetSimple CMS configuration or .htaccess to block SVG file uploads
Add to .htaccess: <FilesMatch "\.svg$">
Order Allow,Deny
Deny from all
</FilesMatch>
Implement server-side SVG sanitization
allAdd server-side validation to strip JavaScript from uploaded SVG files
Implement custom upload handler that parses SVG XML and removes script tags, event handlers, and JavaScript URIs
🧯 If You Can't Patch
- Restrict file upload permissions to trusted administrators only
- Implement Content Security Policy headers to block inline script execution
🔍 How to Verify
Check if Vulnerable:
Check if authenticated users can upload SVG files containing JavaScript that executes when viewedCheck Version:
Check GetSimple CMS version in admin panel or read version.txt fileVerify Fix Applied:
Test that uploaded SVG files with embedded JavaScript no longer execute when accessed📡 Detection & Monitoring
Log Indicators:
- Multiple SVG file uploads from single user
- Large SVG files with unusual content patterns
- Admin panel access from unexpected locations after SVG upload
Network Indicators:
- HTTP requests to uploaded SVG files followed by suspicious outbound connections
- Unusual POST requests to file upload endpoints
SIEM Query:
source="webserver.log" AND (uri="*.svg" OR method="POST" AND uri="*/admin/upload*")