CVE-2026-27247: Adobe Experience Manager XSS Vulnerability

CVE-2026-27247 Overview

Adobe Experience Manager versions 6.5.23 and earlier are affected by a stored Cross-Site Scripting (XSS) vulnerability that could be abused by a low-privileged attacker to inject malicious scripts into vulnerable form fields. Malicious JavaScript may be executed in a victim's browser when they browse to the page containing the vulnerable field.

Critical Impact

Authenticated attackers with low privileges can inject persistent malicious scripts that execute in victims' browsers, potentially enabling session hijacking, credential theft, and unauthorized actions on behalf of legitimate users.

Affected Products

• Adobe Experience Manager versions 6.5.23 and earlier
• Adobe Experience Manager 6.5 LTS (all service packs)
• Adobe Experience Manager AEM Cloud Service

Discovery Timeline

• 2026-03-11 - CVE-2026-27247 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-27247

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting (XSS). The stored XSS variant is particularly dangerous because the malicious payload persists on the server and is delivered to every user who accesses the affected page.

Adobe Experience Manager is a comprehensive content management solution used by enterprises to build websites, mobile apps, and forms. The vulnerability exists within form field handling where user-supplied input is not properly sanitized before being stored and subsequently rendered to other users.

The attack requires network access and a low-privileged authenticated account, making exploitation feasible for any user with basic access to the AEM authoring environment. The changed scope indicates that the vulnerability can impact resources beyond its security context, affecting end-users viewing the compromised content.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and output encoding within Adobe Experience Manager's form field processing logic. When user input is submitted to vulnerable form fields, the application fails to properly sanitize or encode special characters that have meaning in HTML/JavaScript contexts. This allows script tags and event handlers to be stored in the database and rendered directly in the browser without proper escaping.

Attack Vector

The attack proceeds through the following mechanism:

1. An attacker with low-level privileges authenticates to the Adobe Experience Manager instance
2. The attacker identifies vulnerable form fields that accept and store user input
3. Malicious JavaScript code is injected into these fields, such as script tags or event handlers
4. The payload is stored persistently in the AEM content repository
5. When legitimate users browse to pages containing the vulnerable field, their browsers execute the malicious script
6. The script runs in the context of the victim's authenticated session, enabling session theft, phishing overlays, or unauthorized actions

The stored nature of this XSS vulnerability means the payload persists and affects all users who view the compromised content, amplifying the potential impact significantly compared to reflected XSS attacks.

Detection Methods for CVE-2026-27247

Indicators of Compromise

• Unusual JavaScript code or script tags appearing in form field values within the AEM content repository
• Unexpected HTTP requests to external domains from user browsers after loading AEM-hosted pages
• Encoded payloads containing <script>, javascript:, or event handlers like onerror, onload in stored content
• User reports of unexpected browser behavior or pop-ups when accessing specific AEM pages

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS patterns in form submissions
• Review AEM audit logs for suspicious content modifications by low-privileged users
• Deploy Content Security Policy (CSP) headers to detect and report inline script execution attempts
• Conduct periodic content scanning of the JCR repository for stored XSS indicators

Monitoring Recommendations

• Enable and monitor AEM audit logging for all content authoring activities
• Configure browser-based CSP reporting to a centralized security monitoring system
• Establish baseline behavior for form field usage and alert on anomalous patterns
• Monitor network traffic for unexpected outbound connections originating from AEM-served pages

How to Mitigate CVE-2026-27247

Immediate Actions Required

• Apply the latest Adobe Experience Manager security update as referenced in Adobe Security Advisory APSB26-24
• Review and audit existing content for signs of injected scripts in form fields
• Implement Content Security Policy (CSP) headers to restrict inline script execution
• Restrict access to form authoring capabilities to only trusted users

Patch Information

Adobe has released a security update addressing this vulnerability. Organizations should consult Adobe Security Advisory APSB26-24 for complete patch details and upgrade instructions. For AEM 6.5 LTS environments, ensure the latest service pack is applied. AEM Cloud Service customers should verify their instances have received the automatic security update.

Workarounds

• Deploy a Web Application Firewall (WAF) with XSS filtering rules to block malicious payloads at the network perimeter
• Implement strict Content Security Policy headers: Content-Security-Policy: default-src 'self'; script-src 'self'
• Restrict form field authoring permissions to minimize the attack surface until patching is complete
• Conduct a manual audit of form fields and sanitize any suspicious content found in the repository

# Example Content Security Policy configuration for Apache
# Add to httpd.conf or .htaccess
Header always set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'self';"