CVE-2026-27253: Adobe Experience Manager XSS Vulnerability

CVE-2026-27253 Overview

Adobe Experience Manager (AEM) versions 6.5.23 and earlier are affected by a stored Cross-Site Scripting (XSS) vulnerability that allows a low-privileged attacker to inject malicious scripts into vulnerable form fields. When unsuspecting users browse to pages containing the compromised fields, the attacker's malicious JavaScript executes in the victim's browser context, potentially enabling session hijacking, credential theft, or unauthorized actions on behalf of the victim.

Critical Impact

Low-privileged attackers can persistently inject malicious scripts that execute in victim browsers, enabling session hijacking, data theft, and unauthorized actions within the AEM platform.

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-2026-27253 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-27253

Vulnerability Analysis

This stored Cross-Site Scripting (XSS) vulnerability (CWE-79) affects Adobe Experience Manager's form field handling functionality. Unlike reflected XSS attacks that require victims to click malicious links, stored XSS vulnerabilities persist within the application's data storage, making them particularly dangerous. Once an attacker successfully injects malicious JavaScript into a vulnerable form field, the payload is stored server-side and subsequently served to any user who views the affected page.

The vulnerability requires low-privilege access to exploit, meaning authenticated users with minimal permissions can inject malicious content. The attack operates over the network and requires user interaction—specifically, a victim must browse to the page containing the compromised field for the attack to succeed. The cross-site scope of this vulnerability means the malicious script can potentially impact resources beyond the vulnerable component itself.

Root Cause

The root cause of CVE-2026-27253 lies in insufficient input sanitization and output encoding within Adobe Experience Manager's form field processing logic. When user-supplied content is stored in form fields, the application fails to properly validate and sanitize the input for potentially malicious script content. Additionally, when this stored content is rendered back to users, proper output encoding is not applied, allowing the injected scripts to execute in the browser context.

Attack Vector

The attack vector for this vulnerability involves network-based exploitation where an authenticated attacker with low privileges submits crafted input containing malicious JavaScript to vulnerable form fields within Adobe Experience Manager. The attack flow proceeds as follows:

1. The attacker authenticates to AEM with minimal privileges
2. The attacker identifies vulnerable form fields that accept user input
3. Malicious JavaScript payloads are injected into these form fields
4. The payload is stored in the AEM content repository
5. When victims (including administrators) view pages containing the compromised fields, the malicious JavaScript executes in their browser
6. The attacker can then steal session cookies, perform actions as the victim, or redirect users to malicious sites

The malicious scripts execute within the security context of the AEM application, potentially allowing attackers to access sensitive data, modify content, or escalate privileges by targeting administrative users.

Detection Methods for CVE-2026-27253

Indicators of Compromise

• Unexpected JavaScript code or HTML tags found in AEM form field content stored in the JCR repository
• Unusual user activity patterns following form submissions, particularly from low-privileged accounts
• Browser console errors or unexpected script execution reported by users viewing AEM-managed pages
• Anomalous outbound network requests originating from client browsers when viewing AEM content

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS payloads in form submissions
• Enable detailed logging for AEM form field submissions and review logs for suspicious input patterns
• Deploy Content Security Policy (CSP) headers to restrict script execution and report violations
• Utilize browser-based XSS auditing tools and security scanners to identify stored XSS vulnerabilities

Monitoring Recommendations

• Monitor AEM access logs for unusual form submission patterns from low-privileged accounts
• Configure CSP violation reporting to detect attempted XSS payload executions
• Implement real-time alerting for content modifications containing script-like patterns
• Review JCR node changes for unexpected script content in user-editable fields

How to Mitigate CVE-2026-27253

Immediate Actions Required

• Apply the security update referenced in Adobe Security Advisory APSB26-24
• Audit existing form field content in the JCR repository for potentially malicious script injections
• Implement Content Security Policy headers to mitigate the impact of any existing stored XSS payloads
• Review and restrict permissions for low-privileged users who can submit form content

Patch Information

Adobe has released security updates addressing this vulnerability. Organizations running affected versions of Adobe Experience Manager should immediately apply the patches detailed in Adobe Security Advisory APSB26-24. For AEM 6.5, upgrade to a version newer than 6.5.23. Organizations using AEM Cloud Service should ensure their instances are updated to the latest release.

Workarounds

• Implement strict input validation on all form fields that accept user content, rejecting or encoding special characters
• Deploy Content Security Policy (CSP) headers with strict script-src directives to prevent inline script execution
• Restrict form submission capabilities to only trusted, verified users until patches can be applied
• Enable XSS Protection filters in dispatcher configurations to sanitize potentially malicious content

# Example Apache Dispatcher CSP configuration
<IfModule mod_headers.c>
    Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'self';"
    Header set X-XSS-Protection "1; mode=block"
    Header set X-Content-Type-Options "nosniff"
</IfModule>