CVE-2026-47978: Adobe Experience Manager XSS Vulnerability

CVE-2026-47978 Overview

CVE-2026-47978 is a stored Cross-Site Scripting (XSS) vulnerability affecting Adobe Experience Manager (AEM). The flaw resides in form field handling and allows a low-privileged authenticated attacker to inject malicious JavaScript into vulnerable fields. When a victim navigates to the affected page, the injected script executes in the victim's browser context. The vulnerability has a changed scope, meaning impact extends beyond the vulnerable component. Adobe Experience Manager versions 6.5.24, LTS SP1, 2026.04, and earlier releases are affected. The issue is classified under [CWE-79] Improper Neutralization of Input During Web Page Generation.

Critical Impact
Authenticated attackers can inject persistent JavaScript that executes against any user visiting affected AEM pages, enabling session theft, credential harvesting, and unauthorized actions on behalf of victims.

Affected Products

Adobe Experience Manager 6.5.24 and earlier
Adobe Experience Manager LTS SP1 and earlier
Adobe Experience Manager 2026.04 (AEM Cloud Service) and earlier

Discovery Timeline

2026-06-09 - CVE-2026-47978 published to NVD
2026-06-10 - Last updated in NVD database

Technical Details for CVE-2026-47978

Vulnerability Analysis

The vulnerability is a stored XSS issue in Adobe Experience Manager form components. AEM fails to properly neutralize attacker-controlled input written into form field values before that input is rendered back to other users. Because the malicious payload is persisted on the server, every subsequent visitor to the affected page receives and executes the injected script.

The Common Weakness Enumeration classification is [CWE-79]. Exploitation requires low privileges (PR:L) and user interaction (UI:R) — the victim must browse the page hosting the poisoned field. The scope change (S:C) indicates that the injected script can affect resources beyond the vulnerable AEM component, including any browser-accessible data within the victim's origin context.

Root Cause

The root cause is missing or insufficient output encoding when rendering user-supplied form field content. AEM stores the raw attacker input and later writes it into HTML responses without contextual escaping. Browsers parse the embedded <script> or event-handler payload as executable JavaScript rather than inert text.

Attack Vector

An authenticated attacker with form-editing privileges submits a crafted payload into a vulnerable form field. The payload is persisted in the AEM repository. When an administrator, author, or end user later loads the page containing that field, the browser executes the attacker's JavaScript. Possible outcomes include session cookie theft, forced administrative actions through CSRF chaining, credential capture via injected login overlays, and redirection to attacker-controlled domains.

No public proof-of-concept or exploit code is currently available for CVE-2026-47978. Refer to the Adobe Experience Manager Security Advisory APSB26-56 for vendor technical details.

Detection Methods for CVE-2026-47978

Indicators of Compromise

Form field values in the AEM repository containing <script>, javascript:, onerror=, onload=, or similar HTML/JS constructs.
Unexpected outbound browser requests from authenticated AEM sessions to unfamiliar domains.
Audit log entries showing form modifications by low-privileged accounts followed by access from higher-privileged users.

Detection Strategies

Query the AEM JCR for stored field content matching XSS payload patterns and review form authoring history.
Inspect HTTP response bodies from AEM-rendered pages for unencoded < and > characters within form-derived attributes.
Correlate Content Security Policy (CSP) violation reports with AEM page URLs to surface injection attempts.

Monitoring Recommendations

Enable verbose logging on AEM form submission endpoints and forward logs to a centralized SIEM for pattern analysis.
Monitor authoring activity from low-privileged users, particularly bulk edits to form components.
Track anomalous JavaScript execution and data exfiltration attempts originating from authenticated browser sessions.

How to Mitigate CVE-2026-47978

Immediate Actions Required

Apply the patches referenced in Adobe Security Bulletin APSB26-56 to all on-premises and LTS AEM instances.
Confirm AEM Cloud Service instances are updated to a release later than 2026.04.
Audit existing form fields for already-persisted XSS payloads and remediate before exposing pages to users.

Patch Information

Adobe addresses CVE-2026-47978 in the updates listed in advisory APSB26-56. Administrators should upgrade beyond AEM 6.5.24, AEM LTS SP1, and AEM Cloud Service 2026.04. Validate patch installation by reviewing the AEM version under the system console after deployment.

Workarounds

Restrict form authoring permissions to trusted users until patches are applied, reducing the attacker pool that satisfies the PR:L requirement.
Deploy a strict Content Security Policy that disallows inline scripts and limits script sources to known-good origins.
Place a web application firewall (WAF) in front of AEM with rules that block known XSS payload signatures in form submission requests.

bash

# Example CSP header to limit inline script execution on AEM-served pages
Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self'