CVE-2026-75739: Adobe Experience Manager XSS Vulnerability

CVE-2026-75739 Overview

CVE-2026-75739 is a stored Cross-Site Scripting (XSS) vulnerability affecting Adobe Experience Manager (AEM). A low-privileged authenticated attacker can inject malicious JavaScript into vulnerable form fields. The payload executes in a victim's browser when they load a page containing the affected field. The vulnerability has a changed scope, meaning the injected script can impact resources beyond the vulnerable component.

The flaw is categorized under [CWE-79] Improper Neutralization of Input During Web Page Generation. Adobe published fixes in security advisory APSB26-98, covering both AEM Cloud Service and on-premise AEM 6.5 LTS builds.

Critical Impact
Authenticated attackers with low privileges can persist JavaScript payloads that execute against any user, including administrators, who views the affected page.

Affected Products

Adobe Experience Manager (AEM) Cloud Service
Adobe Experience Manager 6.5 LTS (base release)
Adobe Experience Manager 6.5 LTS Service Pack 1 and Service Pack 2

Discovery Timeline

2026-09-08 - CVE-2026-75739 published to the National Vulnerability Database
2026-09-10 - Last updated in NVD database

Technical Details for CVE-2026-75739

Vulnerability Analysis

Adobe Experience Manager fails to properly neutralize user-supplied input written into form fields. An authenticated author or contributor can submit content containing JavaScript that AEM stores server-side without adequate encoding or sanitization. When a subsequent user renders the page containing that field, the browser interprets the injected markup as executable script.

Because the CVSS vector reports a changed scope, script execution reaches security contexts outside the vulnerable AEM component. This enables session-riding actions against the victim's authenticated session, such as issuing authoring API calls, exfiltrating cookies accessible to the page, or pivoting to administrative interfaces the victim can access.

The EPSS score is 0.271% with a percentile of 19.124, indicating low near-term exploitation probability. However, stored XSS in a content management system is durable and reusable, so risk grows with each unpatched day.

Root Cause

The root cause is missing output encoding or input sanitization on specific form field renderers in AEM. Adobe's advisory does not enumerate the exact component, but the flaw class maps to [CWE-79]. AEM should HTML-encode user-supplied field values before writing them into rendered markup and should validate input against an allowlist of permitted content types.

Attack Vector

The attack requires network access to the AEM instance, low-privileged authenticated access, and user interaction from the victim. A typical sequence: the attacker logs in with author-tier credentials, edits a form component, embeds a payload such as an event-handler attribute or script tag, and saves. When a higher-privileged user opens the page, the browser executes the payload in that user's context.

The vulnerability is described in prose only. Adobe has not released a public proof-of-concept, and no verified exploit code is available in this dataset. Refer to the Adobe Security Advisory APSB26-98 for vendor guidance.

Detection Methods for CVE-2026-75739

Indicators of Compromise

Unexpected <script> tags, on* event-handler attributes, or javascript: URIs stored in AEM content nodes, particularly within form field properties.
AEM audit log entries showing form or component edits by low-privileged authors immediately followed by content publication.
Outbound browser requests from author or publish domains to attacker-controlled hosts, observed in proxy or DNS telemetry.

Detection Strategies

Query the JCR repository for stored field values containing HTML control characters or script keywords using AEM's Query Builder or JCR-SQL2.
Review web server access logs for POST requests to /content/, /bin/, or component edit endpoints followed by GET requests generating anomalous response sizes.
Correlate authoring activity from newly created or low-privilege accounts with subsequent XSS-indicative browser telemetry.

Monitoring Recommendations

Enable Content Security Policy (CSP) reporting on AEM publish instances to capture violations from injected inline scripts.
Forward AEM access, audit, and error logs to a centralized SIEM for correlation with endpoint browser telemetry.
Alert on any modification to form component templates or client libraries by non-administrative accounts.

How to Mitigate CVE-2026-75739

Immediate Actions Required

Apply the updates listed in Adobe Security Advisory APSB26-98 to AEM Cloud Service and AEM 6.5 LTS environments.
Audit existing content and form components for previously injected script payloads before assuming the environment is clean.
Restrict author-tier accounts to the minimum users required and rotate credentials for any account suspected of misuse.

Patch Information

Adobe released fixes in bulletin APSB26-98 covering AEM Cloud Service and AEM 6.5 LTS (base, SP1, SP2). Cloud Service customers receive updates through the automated release channel. On-premise AEM 6.5 LTS operators must download and deploy the corresponding service pack or hotfix package identified in the advisory.

Workarounds

Deploy a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins.
Place a Web Application Firewall (WAF) in front of AEM publish instances with rules that block common XSS payload patterns in form submissions.
Temporarily revoke form component edit permissions from low-privileged author groups until patches are applied and content is reviewed.

bash

# Example CSP header to reduce stored XSS impact on AEM publish
Header always set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self'; report-uri /csp-report"