CVE-2018-4876 in Experience Manager
Summary
by MITRE
Adobe Experience Manager versions 6.3, 6.2, and 6.1 are vulnerable to cross-site scripting via a bypass of the Sling XSSAPI#getValidHref function.
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Analysis
by VulDB Data Team • 01/08/2020
Adobe Experience Manager represents a comprehensive content management platform that serves as a cornerstone for enterprise digital experiences, processing millions of user interactions daily through its robust web application framework. The vulnerability described in CVE-2018-4876 specifically targets the Sling XSSAPI component which forms part of AEM's core security architecture designed to prevent cross-site scripting attacks. This flaw manifests when the getValidHref function fails to properly validate user-supplied input, allowing malicious actors to bypass security controls that should prevent dangerous script execution within the application context.
The technical exploitation of this vulnerability occurs through careful manipulation of URL parameters or form fields that are processed by the Sling XSSAPI component. Attackers can craft malicious inputs that appear legitimate to the validation routines but contain embedded script payloads that ultimately execute in the context of other users browsing the affected AEM instances. The bypass mechanism specifically targets the validation logic within getValidHref, which is responsible for sanitizing and validating hyperlinks to ensure they do not contain malicious content. This represents a critical failure in the application's input validation and sanitization processes that directly violates established security principles for web application protection.
The operational impact of this vulnerability extends far beyond simple script injection, as it enables attackers to perform a wide range of malicious activities including session hijacking, data exfiltration, and privilege escalation within the AEM environment. When exploited successfully, the vulnerability allows attackers to execute arbitrary JavaScript code in the context of authenticated users, potentially leading to complete compromise of the affected systems. The affected versions 6.3, 6.2, and 6.1 represent widely deployed enterprise solutions where this vulnerability could affect thousands of organizations, making the potential attack surface extremely broad and impactful.
Organizations utilizing Adobe Experience Manager must implement immediate mitigation strategies including applying the vendor-provided security patches and updates that address the specific XSS bypass vulnerability in the Sling XSSAPI component. The remediation process should also include enhanced input validation procedures and comprehensive security testing of all user-supplied content processing pathways. Security teams should conduct thorough vulnerability assessments to identify any custom code or extensions that might be vulnerable to similar bypass techniques. This vulnerability aligns with CWE-79 Cross-site Scripting and follows patterns commonly associated with ATT&CK technique T1059.007 Command and Scripting Interpreter: JavaScript, emphasizing the importance of proper input sanitization and validation in web application security controls.
The broader implications of this vulnerability highlight the critical importance of maintaining up-to-date security controls within enterprise content management systems. AEM's extensive use across digital marketing platforms, corporate websites, and customer experience applications means that successful exploitation could result in significant business disruption, data breaches, and regulatory compliance violations. Organizations should also consider implementing additional security layers including web application firewalls and runtime application self-protection mechanisms to provide defense-in-depth against similar vulnerabilities that may exist in other components of their web application stack.