CVE-2020-9742
📋 TL;DR
This stored cross-site scripting (XSS) vulnerability in Adobe Experience Manager allows authenticated users with 'Author' privileges to inject malicious scripts into calendar fields. When other users view pages containing these compromised fields, the scripts execute in their browsers, potentially stealing session cookies or performing unauthorized actions. The vulnerability affects AEM versions 6.5.5.0 and below, 6.4.8.1 and below, and 6.3.3.8 and below.
💻 Affected Systems
- Adobe Experience Manager
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers with author privileges could steal administrator session cookies, gain full administrative access, install backdoors, exfiltrate sensitive data, or compromise user accounts through session hijacking.
Likely Case
Malicious authors inject scripts that steal session cookies from other users, leading to account takeover and unauthorized content manipulation within the AEM environment.
If Mitigated
With proper input validation and output encoding, malicious scripts would be neutralized, preventing execution even if injected into calendar fields.
🎯 Exploit Status
Requires authenticated author access; exploitation is straightforward once access is obtained
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.5.6.0, 6.4.9.0, 6.3.3.9
Vendor Advisory: https://helpx.adobe.com/security/products/experience-manager/apsb20-56.html
Restart Required: Yes
Instructions:
1. Download appropriate AEM service pack from Adobe distribution portal. 2. Stop AEM instance. 3. Install service pack using Package Manager. 4. Restart AEM instance. 5. Verify installation via Package Manager.
🔧 Temporary Workarounds
Disable Inbox Calendar Feature
allRemove or disable the vulnerable Inbox calendar component to prevent exploitation
Navigate to CRXDE Lite
Disable or remove /apps/cq/inbox/calendar components
Implement Content Security Policy
allAdd CSP headers to prevent script execution from untrusted sources
Add Content-Security-Policy header to dispatcher or web server configuration
🧯 If You Can't Patch
- Restrict author privileges to trusted users only and implement strict access controls
- Implement web application firewall rules to block XSS payloads in calendar field submissions
🔍 How to Verify
Check if Vulnerable:
Check AEM version via OSGi console (http://host:port/system/console/bundles) or via CRX Package ManagerCheck Version:
curl -u admin:password http://localhost:4502/system/console/bundles/org.apache.sling.installer.provider.file | grep 'Adobe Experience Manager'Verify Fix Applied:
Verify installed service pack version matches patched versions (6.5.6.0, 6.4.9.0, or 6.3.3.9) in Package Manager📡 Detection & Monitoring
Log Indicators:
- Unusual calendar entry modifications by author users
- Requests containing script tags or JavaScript in calendar field parameters
Network Indicators:
- HTTP requests with suspicious script payloads to /content/calendar endpoints
- Unexpected outbound connections from AEM server after calendar access
SIEM Query:
source="aem-access.log" AND (uri_path="/content/calendar" OR uri_path="/inbox/calendar") AND (message="<script" OR message="javascript:")