CVE-2021-29459
📋 TL;DR
CVE-2021-29459 is a cross-site scripting (XSS) vulnerability in XWiki Platform that allows attackers to inject malicious scripts into text fields. Both unregistered users (in simple text fields) and registered users (in personal information and static lists) can exploit this. The vulnerability affects XWiki versions prior to 12.6.3 and 12.8.
💻 Affected Systems
- XWiki Platform
📦 What is this software?
Xwiki by Xwiki
Xwiki by Xwiki
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal session cookies, perform actions as authenticated users, deface websites, or redirect users to malicious sites, potentially leading to complete account compromise.
Likely Case
Attackers inject malicious scripts to steal user session cookies or credentials, leading to unauthorized access to user accounts.
If Mitigated
With proper input validation and output encoding, script injection would be prevented, limiting impact to minor data manipulation.
🎯 Exploit Status
Unregistered users can exploit simple text fields; registered users can exploit additional fields. No public exploit code known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: XWiki 12.6.3 or 12.8
Vendor Advisory: https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-5c66-v29h-xjh8
Restart Required: Yes
Instructions:
1. Backup your XWiki instance. 2. Upgrade to XWiki 12.6.3 or 12.8. 3. Restart the XWiki service. 4. Verify the upgrade was successful.
🔧 Temporary Workarounds
No effective workaround
allThe vendor states there is no easy workaround except upgrading.
🧯 If You Can't Patch
- Implement strict input validation and output encoding for all user inputs.
- Use Content Security Policy (CSP) headers to restrict script execution.
🔍 How to Verify
Check if Vulnerable:
Check XWiki version; if it's below 12.6.3 or 12.8, it's vulnerable.Check Version:
Check the XWiki administration panel or version file in the installation directory.Verify Fix Applied:
Verify the XWiki version is 12.6.3 or 12.8 or higher after upgrade.📡 Detection & Monitoring
Log Indicators:
- Unusual script tags or JavaScript in user input fields in application logs.
- Multiple failed login attempts or session hijacking events.
Network Indicators:
- Unexpected outbound connections to external domains from user sessions.
- Suspicious HTTP requests containing script payloads.
SIEM Query:
Search for patterns like '<script>' or 'javascript:' in user input fields in web application logs.