CVE-2021-44176
📋 TL;DR
This stored XSS vulnerability in Adobe Experience Manager allows attackers to inject malicious JavaScript into vulnerable form fields. When users visit pages containing these compromised fields, their browsers execute the attacker's scripts. This affects AEM Cloud Service and AEM 6.5.10.0 and earlier versions.
💻 Affected Systems
- Adobe Experience Manager (AEM)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal session cookies, perform actions as authenticated users, redirect to malicious sites, or install malware on user systems.
Likely Case
Session hijacking, credential theft, defacement of web pages, or redirection to phishing sites.
If Mitigated
Limited impact with proper input validation, output encoding, and Content Security Policy (CSP) headers in place.
🎯 Exploit Status
Requires ability to submit malicious input to vulnerable form fields, which typically requires some level of access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: AEM 6.5.11.0 or later
Vendor Advisory: https://helpx.adobe.com/security/products/experience-manager/apsb21-103.html
Restart Required: Yes
Instructions:
1. Download AEM 6.5.11.0 or later from Adobe. 2. Apply the service pack or upgrade to the patched version. 3. Restart AEM services. 4. Verify the fix by testing previously vulnerable form fields.
🔧 Temporary Workarounds
Input Validation and Output Encoding
allImplement server-side input validation and proper output encoding for all user-controlled data.
Content Security Policy
allImplement strict CSP headers to prevent execution of unauthorized scripts.
🧯 If You Can't Patch
- Implement WAF rules to block XSS payloads in form submissions
- Disable or restrict access to vulnerable form fields until patching is possible
🔍 How to Verify
Check if Vulnerable:
Test form fields by submitting XSS payloads like <script>alert('XSS')</script> and check if they execute when the page loads.Check Version:
Check AEM version via the AEM welcome page or system console.Verify Fix Applied:
After patching, test the same XSS payloads to confirm they are properly sanitized and don't execute.📡 Detection & Monitoring
Log Indicators:
- Unusual form submissions containing script tags or JavaScript code
- Multiple failed login attempts following suspicious form submissions
Network Indicators:
- HTTP requests containing XSS payload patterns in POST data
SIEM Query:
source="aem_logs" AND ("<script>" OR "javascript:" OR "onerror=" OR "onload=")