CVE-2022-28851 is a reflected Cross-Site Scripting (XSS) vulnerability identified in Adobe Experience Manager (AEM), specifically affecting version 6.5.13.0 and earlier. Reflected XSS vulnerabilities occur when untrusted user input is immediately returned by a web application without proper sanitization or encoding, allowing an attacker to inject malicious JavaScript code that executes in the context of the victim's browser. In this case, an attacker can craft a malicious URL referencing a vulnerable page within AEM. When a victim with low-privilege access to the AEM instance clicks this URL, the malicious script executes, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim. The vulnerability requires the attacker to have low-privilege access to the AEM environment, which implies that the attacker must at least be able to interact with the application in some capacity, such as a logged-in user or through publicly accessible pages that reflect input parameters. There are no known exploits in the wild at the time of reporting, and no official patches have been linked, indicating that remediation may require manual mitigation or awaiting vendor updates. The vulnerability is categorized under CWE-79, which is a common and well-understood web application security flaw. Given the nature of AEM as a content management system widely used by enterprises for managing digital assets and websites, exploitation could lead to significant reputational damage and data exposure if malicious scripts are used to compromise user sessions or deface websites.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Adobe Experience Manager to manage public-facing websites or internal portals. Successful exploitation could allow attackers to execute arbitrary JavaScript in the browsers of users interacting with the vulnerable AEM instance, potentially leading to theft of authentication tokens, redirection to malicious sites, or unauthorized actions performed with the victim's privileges. This can result in data breaches, loss of customer trust, and regulatory non-compliance under GDPR due to exposure of personal data. Additionally, if internal users are targeted, attackers could leverage the XSS to escalate privileges or move laterally within the network. The requirement for low-privilege access somewhat limits the attack surface but does not eliminate risk, as many AEM deployments have publicly accessible components or user roles with minimal restrictions. The absence of known active exploits reduces immediate risk but does not preclude targeted attacks, especially against high-value European organizations such as government agencies, financial institutions, and large enterprises that use AEM extensively.

1. Immediate mitigation should include implementing strict input validation and output encoding on all user-supplied data reflected in web pages to prevent injection of malicious scripts. 2. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS attacks. 3. Review and tighten access controls within AEM to minimize low-privilege access that could be leveraged by attackers. 4. Monitor web server and application logs for unusual URL patterns or repeated attempts to exploit reflected input parameters. 5. Educate users and administrators about the risks of clicking suspicious links, especially those referencing internal AEM pages. 6. Regularly update AEM to the latest versions once Adobe releases patches addressing this vulnerability. 7. Use web application firewalls (WAFs) with rules specifically designed to detect and block reflected XSS payloads targeting AEM. 8. Conduct security assessments and penetration testing focused on XSS vulnerabilities in AEM deployments to identify and remediate similar issues proactively.