CVE-2020-9734 in Experience Manager
Summary
by MITRE
The AEM Forms add-on for versions 6.5.5.0 (and below) and 6.4.8.1 (and below) is affected by a stored XSS vulnerability that allows users with 'Author' privileges to store malicious scripts in fields associated with the Forms component. These scripts may be executed in a victim’s browser when they open the page containing the vulnerable field.
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Analysis
by VulDB Data Team • 11/13/2020
The vulnerability CVE-2020-9734 represents a critical stored cross-site scripting flaw within Adobe Experience Manager Forms add-on components. This security weakness affects specific versions of AEM Forms including 6.5.5.0 and earlier releases, as well as 6.4.8.1 and below, making it a widespread concern for organizations utilizing these software versions. The vulnerability resides in the way the system handles user input within Forms component fields, creating an environment where malicious actors can inject persistent script code that executes in the browsers of unsuspecting users who access affected pages.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding mechanisms within the AEM Forms processing pipeline. When users with 'Author' privileges create or modify content within Forms components, the system fails to properly sanitize or escape user-supplied data before storing it in the repository. This allows attackers to inject malicious JavaScript code directly into form fields, which are then stored persistently within the application's data store. The stored scripts remain dormant until accessed by other users, at which point they execute within the victim's browser context, potentially compromising user sessions and data confidentiality.
The operational impact of this vulnerability extends beyond simple script execution, creating significant risks for enterprise environments that rely on AEM Forms for business-critical processes. Attackers with 'Author' privileges can leverage this weakness to perform session hijacking, steal sensitive user credentials, redirect victims to malicious websites, or even execute more sophisticated attacks such as privilege escalation within the application. The stored nature of the vulnerability means that the malicious code can affect multiple users over time, making it particularly dangerous for environments where forms are frequently accessed by numerous employees or customers. This vulnerability directly maps to CWE-79, which defines cross-site scripting flaws, and aligns with ATT&CK technique T1566 for initial access through malicious content.
Organizations affected by CVE-2020-9734 should immediately implement comprehensive mitigation strategies to address this security gap. The primary recommendation involves upgrading to patched versions of AEM Forms that contain proper input sanitization and output encoding mechanisms. Additionally, administrators should enforce strict access controls to limit 'Author' privileges to trusted personnel only, implement web application firewalls to detect and block malicious script patterns, and conduct thorough security assessments of existing forms to identify and remediate any stored malicious content. Regular security monitoring and user education programs should also be established to detect potential exploitation attempts and maintain overall system security posture.