CVE-2026-75657: Adobe Experience Manager DOM-Based XSS Flaw

CVE-2026-75657 Overview

CVE-2026-75657 is a DOM-based Cross-Site Scripting (XSS) vulnerability affecting Adobe Experience Manager (AEM). An attacker can manipulate the Document Object Model (DOM) environment to execute arbitrary JavaScript within the context of a victim's browser session. Successful exploitation requires user interaction, as the victim must visit a crafted webpage. The vulnerability carries a changed scope, meaning impact extends beyond the vulnerable component to affect other security authorities. The flaw is categorized under [CWE-79] Improper Neutralization of Input During Web Page Generation.

Critical Impact
Successful exploitation allows execution of malicious JavaScript in the victim's browser, enabling session theft, credential harvesting, and unauthorized actions in the AEM context.

Affected Products

Adobe Experience Manager (AEM) — refer to the Adobe Experience Manager Security Advisory for specific affected versions

Discovery Timeline

2026-09-08 - CVE-2026-75657 published to the National Vulnerability Database (NVD)
2026-09-10 - Last updated in NVD database

Technical Details for CVE-2026-75657

Vulnerability Analysis

CVE-2026-75657 is a client-side XSS flaw where untrusted input flows into a DOM sink without proper sanitization. The vulnerable code path executes attacker-controlled data as JavaScript within the victim's browser. Because the flaw is DOM-based, the malicious payload does not need to touch the server, which limits server-side detection opportunities.

The changed scope indicates that a successful attack can affect resources beyond the AEM component itself. An attacker leveraging this weakness in an authenticated AEM environment can pivot to browser-accessible resources under the victim's authority. The flaw requires a low-privileged authenticated session on the AEM instance and social engineering to lure the victim to a crafted URL.

Root Cause

The root cause is improper neutralization of user-supplied input written to a DOM sink such as innerHTML, document.write, or eval. AEM client-side JavaScript reads attacker-controlled values from sources such as URL parameters, fragments, or postMessage data and passes them directly to an execution sink. This missing sanitization allows arbitrary script execution when the crafted content is rendered.

Attack Vector

An attacker crafts a malicious URL or webpage that triggers the vulnerable AEM client-side logic. The victim, who must hold a valid low-privileged AEM session, is lured to the crafted page through phishing or another social engineering vector. Once loaded, the injected JavaScript executes in the victim's browser under the AEM origin. The attacker can then read authenticated content, perform actions on behalf of the victim, or exfiltrate session data. The vulnerability mechanism is documented in the Adobe Experience Manager Security Advisory.

Detection Methods for CVE-2026-75657

Indicators of Compromise

Unusual URL parameters or URL fragments containing HTML tags, javascript: schemes, or encoded script payloads targeting AEM endpoints
Outbound browser requests to attacker-controlled domains originating from authenticated AEM sessions
Unexpected POST requests from AEM users performing sensitive operations shortly after visiting external links

Detection Strategies

Deploy Content Security Policy (CSP) reporting to capture inline script violations from AEM origins
Inspect web server and reverse proxy logs for anomalous query strings targeting AEM authoring or preview endpoints
Correlate email gateway phishing telemetry with subsequent AEM session activity to identify targeted lures

Monitoring Recommendations

Monitor browser DOM sinks through client-side runtime protection or Real User Monitoring (RUM) instrumentation
Track authenticated AEM user behavior for anomalous administrative actions or data access patterns
Alert on newly registered lookalike domains impersonating the organization's AEM properties

How to Mitigate CVE-2026-75657

Immediate Actions Required

Apply the Adobe security update referenced in APSB26-98 to all AEM instances
Inventory all internet-facing and internal AEM deployments to confirm patch coverage
Notify AEM authors and administrators about the phishing risk and reinforce link-handling guidance

Patch Information

Adobe has published a security bulletin addressing CVE-2026-75657. Administrators should consult the Adobe Experience Manager Security Advisory for the fixed version numbers, download locations, and upgrade instructions applicable to their deployment model (AEM Cloud Service, AEM on-premises, or AEM Managed Services).

Workarounds

Enforce a strict Content Security Policy that blocks inline scripts and restricts script sources to trusted origins on AEM domains
Restrict AEM authoring interfaces to trusted networks or VPN access to reduce the exposed attack surface
Require multi-factor authentication for all AEM accounts to limit the value of hijacked sessions

bash

# Configuration example: apply a restrictive Content Security Policy header at the AEM dispatcher or reverse proxy
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"
Header always set X-Content-Type-Options "nosniff"
Header always set Referrer-Policy "strict-origin-when-cross-origin"