CVE-2021-28628 in Experience Manager Cloud Service
Summary
by MITRE • 08/25/2021
Adobe Experience Manager Cloud Service offering, as well as versions 6.5.8.0 (and below) is affected by a Cross-Site Scripting (XSS) vulnerability that could be abused by an attacker to inject malicious scripts into vulnerable form fields. Malicious JavaScript may be executed in a victim’s browser when they browse to the page containing the vulnerable field.
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Analysis
by VulDB Data Team • 09/19/2025
Adobe Experience Manager Cloud Service and versions 6.5.8.0 and below contain a cross-site scripting vulnerability that allows attackers to inject malicious scripts into form fields. This vulnerability falls under CWE-79 which represents Cross-Site Scripting, a critical web application security weakness that enables attackers to execute unauthorized scripts in user browsers. The flaw exists in the handling of user input within form fields, where insufficient validation and sanitization permits malicious code to be stored and subsequently executed when victims interact with the affected pages. The vulnerability is particularly concerning as it can be exploited through user-facing interfaces where form data is processed and rendered without proper security measures. Attackers can leverage this weakness to perform session hijacking, deface websites, steal sensitive information, or redirect users to malicious domains. The impact extends beyond simple data theft as it can lead to complete compromise of user sessions and potential lateral movement within affected networks. This vulnerability aligns with ATT&CK technique T1059.007 which covers scripting through web shells, and T1566 which encompasses social engineering attacks using malicious payloads. The XSS flaw represents a fundamental breakdown in input validation and output encoding practices, where user-supplied data is not properly escaped or filtered before being rendered in web pages. Organizations using these Adobe Experience Manager versions face significant risk as the vulnerability can be exploited through various attack vectors including web forms, comment sections, and any input fields that accept user data. The exploitation requires minimal technical skill and can be automated, making it particularly dangerous for widespread impact. Security practitioners should note that this vulnerability demonstrates the critical importance of implementing proper content security policies and robust input sanitization measures. The affected systems lack adequate protection against malicious script injection, creating a persistent threat vector that can be exploited repeatedly until properly patched. Organizations must prioritize immediate remediation through official Adobe security updates and implement additional protective measures such as web application firewalls and enhanced input validation protocols.
The vulnerability manifests when user input containing malicious scripts is submitted through form fields and subsequently displayed without proper sanitization. This creates a persistent XSS vector that can be triggered whenever users view pages containing the compromised data. The attack surface includes any interactive elements within the Adobe Experience Manager platform that process user input, particularly those that do not implement proper HTML escaping or content security policy enforcement. Security controls such as CSP headers and output encoding mechanisms appear to be insufficient or improperly configured in the affected versions, allowing malicious payloads to bypass security checks. The exploitation process typically involves crafting malicious input that includes script tags or other XSS payloads, submitting this through the vulnerable form, and then waiting for victims to view the page containing the stored malicious content. This vulnerability can be classified as a persistent XSS attack under the ATT&CK framework, as the malicious scripts remain stored on the server and can affect multiple users over time. The weakness represents a failure in the principle of least privilege and proper data validation, where user input is not treated as potentially malicious and is directly rendered without appropriate security filtering. Organizations should implement comprehensive monitoring and logging of form submissions to detect potential exploitation attempts. The vulnerability's impact is amplified by the fact that Adobe Experience Manager is commonly used for content management and customer-facing applications, increasing the potential attack surface and exposure to malicious actors. This flaw underscores the critical need for regular security assessments and prompt patch management procedures to prevent exploitation of known vulnerabilities. The technical implementation of input validation should adhere to industry standards such as OWASP Top Ten and NIST guidelines for web application security to prevent similar weaknesses from occurring in future deployments.