CVE-2026-75733 Overview
Adobe Experience Manager (AEM) contains a stored Cross-Site Scripting (XSS) vulnerability [CWE-79] that allows a low-privileged authenticated attacker to inject malicious JavaScript into vulnerable form fields. When a victim navigates to a page rendering the affected field, the injected script executes in the victim's browser under the AEM origin. The vulnerability changes scope, meaning impact extends beyond the vulnerable component to other security domains. Adobe published advisory APSB26-98 addressing the issue across AEM 6.5 LTS service packs and AEM Cloud Service.
Critical Impact
Authenticated attackers can persist malicious scripts in AEM content, enabling session hijacking, credential theft, or unauthorized actions against higher-privileged users who view the affected pages.
Affected Products
- Adobe Experience Manager Cloud Service (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-2026-75733 published to the National Vulnerability Database
- 2026-09-10 - Last updated in the NVD database
Technical Details for CVE-2026-75733
Vulnerability Analysis
The flaw is a stored (persistent) XSS issue within AEM form field handling. An authenticated user with low privileges can submit input containing HTML or JavaScript payloads that AEM stores server-side without adequate output encoding. When another user renders the page containing the injected field, the browser executes the attacker-controlled script in the context of the AEM domain.
Because the CVSS vector indicates a changed scope, the vulnerable component (the form rendering context) allows the payload to affect resources in a different security scope, such as an authenticated administrative session. The attack requires user interaction from the victim, typically loading the affected page. Exploitation does not require any privileged CMS role, only an account permitted to write to the vulnerable form field.
Root Cause
The root cause is improper neutralization of input during web page generation [CWE-79]. AEM fails to sanitize or context-encode user-supplied data written into specific form field components before that data is rendered back into the DOM. Any HTML tags, event handlers, or <script> blocks in the stored value are interpreted by the browser as executable markup rather than inert text.
Attack Vector
An attacker authenticates to AEM with any account permitted to submit or edit the vulnerable form fields. They inject a JavaScript payload, such as an event handler within an attribute or an inline script tag, into the field. AEM persists the payload in the repository. When a victim, often an editor or administrator reviewing submissions, loads the page containing the tainted field, the browser executes the payload. The attacker can then steal session cookies, perform actions in the victim's context, or pivot to further compromise. Refer to the Adobe Security Advisory APSB26-98 for vendor-supplied details.
Detection Methods for CVE-2026-75733
Indicators of Compromise
- Form field values in the AEM repository containing HTML tags such as <script>, <img onerror=>, <svg onload=>, or JavaScript URIs.
- Unexpected outbound requests from author or publish instances to attacker-controlled domains referenced by injected payloads.
- Author or administrator sessions issuing repository writes that do not match their normal workflow patterns, suggesting a hijacked session.
Detection Strategies
- Review AEM access logs for form submissions containing script-like syntax or encoded variants of <, >, and javascript:.
- Scan JCR content nodes associated with form components for stored values that include HTML control characters or event handler attributes.
- Enable and monitor Content Security Policy (CSP) violation reports to surface script execution originating from unexpected inline sources.
Monitoring Recommendations
- Alert on repository writes to form component properties from low-privileged accounts that include HTML or JavaScript syntax.
- Track browser-side errors and CSP reports from AEM author consoles to identify script execution attempts against internal reviewers.
- Correlate authenticated form submissions with subsequent administrative session activity to detect session-riding chains.
How to Mitigate CVE-2026-75733
Immediate Actions Required
- Apply the fixed versions listed in Adobe Security Advisory APSB26-98 to AEM 6.5 LTS and validate that AEM Cloud Service instances have received the vendor-managed update.
- Audit existing form field content for stored payloads before restoring public access to affected pages.
- Restrict form submission privileges to trusted accounts until patching is complete.
Patch Information
Adobe released fixed builds for AEM 6.5 LTS (including base, SP1, and SP2) and the AEM Cloud Service through advisory APSB26-98. AEM Cloud Service customers receive the fix through Adobe's managed release channel. On-premises AEM 6.5 LTS operators must download and deploy the corresponding service pack or cumulative fix pack referenced in the advisory.
Workarounds
- Enforce a strict Content Security Policy on AEM author and publish instances to block inline script execution and restrict script sources.
- Deploy a web application firewall rule that inspects form submissions for HTML tags and JavaScript event handler patterns and rejects or sanitizes them.
- Reduce the privilege of accounts that can submit form content and require review by higher-privileged users only in browsers with script execution restricted for the AEM domain.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
