CVE-2021-28628 is a Cross-Site Scripting (XSS) vulnerability identified in Adobe Experience Manager (AEM), specifically affecting the Cloud Service offering and versions 6.5.8.0 and below. The vulnerability arises from insufficient input validation or output encoding in certain form fields within AEM, allowing an attacker to inject malicious JavaScript code. When a victim accesses a page containing the vulnerable form field, the injected script executes in their browser context. This can lead to a range of malicious activities, including session hijacking, credential theft, unauthorized actions on behalf of the user, or redirection to malicious sites. The vulnerability is classified under CWE-79, which pertains to improper neutralization of input during web page generation. Although no public exploits have been reported in the wild, the risk remains significant due to the widespread use of AEM in enterprise web content management. The lack of available patches or updates at the time of reporting further increases exposure. Attackers do not require authentication to exploit this vulnerability, and exploitation only requires the victim to visit a crafted page or interact with a compromised form field. The vulnerability impacts the confidentiality and integrity of user data and can also affect availability if leveraged in combination with other attacks.

For European organizations, the impact of this XSS vulnerability in Adobe Experience Manager can be considerable. AEM is widely used by large enterprises, government agencies, and public sector organizations across Europe for managing digital content and customer experiences. Exploitation could lead to unauthorized access to sensitive information, including personal data protected under GDPR, resulting in regulatory penalties and reputational damage. Additionally, attackers could use the vulnerability to perform phishing attacks or deliver malware payloads to users, potentially compromising internal networks. The integrity of web applications and trust in digital services could be undermined, particularly for sectors such as finance, healthcare, and public administration that rely heavily on secure web platforms. The availability of services could also be indirectly affected if attackers leverage XSS to conduct further attacks such as session fixation or privilege escalation. Given the lack of known exploits, the immediate risk is moderate, but the potential for targeted attacks against high-value European entities remains significant.

Implement strict input validation and output encoding on all form fields within Adobe Experience Manager to prevent injection of malicious scripts. Apply Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of any successful XSS attempts. Regularly monitor and audit web application logs for unusual input patterns or suspicious activities indicative of attempted XSS exploitation. Isolate critical administrative interfaces of AEM behind additional authentication layers and network segmentation to limit exposure. Educate users and administrators about the risks of XSS and encourage cautious behavior when interacting with web forms and links. Deploy web application firewalls (WAFs) with updated rulesets capable of detecting and blocking XSS payloads targeting AEM. Stay informed about Adobe’s security advisories and apply patches or updates promptly once available to remediate the vulnerability. Conduct regular security assessments and penetration testing focusing on web application vulnerabilities, including XSS, to identify and remediate weaknesses proactively.