CVE-2021-32808
📋 TL;DR
CVE-2021-32808 is a cross-site scripting (XSS) vulnerability in CKEditor 4 that allows attackers to execute arbitrary JavaScript code by exploiting a flaw in the clipboard Widget plugin when used with the undo feature. It affects all users running CKEditor 4 version 4.13.0 or higher with the vulnerable plugins enabled. The vulnerability enables client-side code execution in the context of the affected web application.
💻 Affected Systems
- CKEditor 4
📦 What is this software?
Ckeditor by Ckeditor
Documaker by Oracle
Documaker by Oracle
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
Financial Services Analytical Applications Infrastructure by Oracle
View all CVEs affecting Financial Services Analytical Applications Infrastructure →
Financial Services Model Management And Governance by Oracle
View all CVEs affecting Financial Services Model Management And Governance →
Financial Services Model Management And Governance by Oracle
View all CVEs affecting Financial Services Model Management And Governance →
Peoplesoft Enterprise Peopletools by Oracle
Peoplesoft Enterprise Peopletools by Oracle
Peoplesoft Enterprise Peopletools by Oracle
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of user sessions, credential theft, defacement of web applications, and potential pivot to backend systems if combined with other vulnerabilities.
Likely Case
Session hijacking, credential theft, and client-side data exfiltration from users interacting with malicious content.
If Mitigated
Limited impact if proper content security policies (CSP) are implemented and user input is sanitized elsewhere in the application stack.
🎯 Exploit Status
Exploitation requires user interaction with malicious content but doesn't require authentication. Proof of concept is available in public advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.16.2
Vendor Advisory: https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-6226-h7ff-ch6c
Restart Required: No
Instructions:
1. Update CKEditor 4 to version 4.16.2 or later. 2. Replace existing CKEditor files with patched version. 3. Clear browser caches and CDN caches if applicable. 4. Test editor functionality after update.
🔧 Temporary Workarounds
Disable vulnerable plugins
allTemporarily disable clipboard Widget plugin or undo feature if not essential
Modify CKEditor configuration to remove 'clipboard' and/or 'undo' from plugins list
Implement Content Security Policy
allAdd strict CSP headers to prevent script execution
Add Content-Security-Policy header with script-src 'self' or stricter directives
🧯 If You Can't Patch
- Implement strict input validation and output encoding for all user-generated content
- Deploy web application firewall (WAF) rules to detect and block XSS payloads
🔍 How to Verify
Check if Vulnerable:
Check CKEditor version in source code or configuration files. If version is 4.13.0 to 4.16.1 and clipboard/undo plugins are enabled, system is vulnerable.Check Version:
Check CKEditor source files for version number or examine web page source for CKEditor version referencesVerify Fix Applied:
Confirm CKEditor version is 4.16.2 or later and test editor functionality with sample malicious content.📡 Detection & Monitoring
Log Indicators:
- Unusual editor content submissions containing script tags or JavaScript payloads
- Multiple undo/redo operations with malformed HTML
Network Indicators:
- HTTP requests containing CKEditor-specific parameters with script payloads
- Unusual outbound connections from editor pages
SIEM Query:
web_requests WHERE url CONTAINS 'ckeditor' AND (body CONTAINS '<script>' OR body CONTAINS 'javascript:' OR body CONTAINS 'onload=')🔗 References
- https://github.com/ckeditor/ckeditor4/releases/tag/4.16.2
- https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-6226-h7ff-ch6c
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NYA354LJP47KCVJMTUO77ZCX3ZK42G3T/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UVOYN2WKDPLKCNILIGEZM236ABQASLGW/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WAGNWHFIQAVCP537KFFS2A2GDG66J7XD/
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://github.com/ckeditor/ckeditor4/releases/tag/4.16.2
- https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-6226-h7ff-ch6c
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NYA354LJP47KCVJMTUO77ZCX3ZK42G3T/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UVOYN2WKDPLKCNILIGEZM236ABQASLGW/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WAGNWHFIQAVCP537KFFS2A2GDG66J7XD/
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
