CVE-2025-64857 is a stored Cross-Site Scripting (XSS) vulnerability identified in Adobe Experience Manager (AEM) versions 6.5.23 and earlier. This vulnerability arises from insufficient sanitization of user-supplied input in certain form fields, allowing a low-privileged attacker to inject malicious JavaScript code that is persistently stored on the server. When other users browse pages containing these vulnerable fields, the malicious script executes in their browsers within the security context of the affected site. This can lead to theft of session cookies, user impersonation, unauthorized actions, or content manipulation. The vulnerability requires the attacker to have low privileges to submit malicious input and requires victims to interact with the affected pages, as indicated by the CVSS vector (AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N). The scope is changed (S:C), meaning the vulnerability can affect resources beyond the vulnerable component. Although no known exploits have been reported in the wild, the medium CVSS score of 5.4 reflects the moderate risk posed by this vulnerability. Adobe has not yet published patches or mitigation details, so organizations must rely on best practices such as input validation and output encoding to reduce risk. Given the widespread use of AEM in enterprise and government websites, this vulnerability could be leveraged to target users accessing these services.

For European organizations, the impact of CVE-2025-64857 can be significant, especially for those relying on Adobe Experience Manager for public-facing websites or internal portals. Exploitation could lead to unauthorized disclosure of sensitive information such as session tokens or personal data, enabling attackers to impersonate users or escalate privileges. This undermines confidentiality and integrity of web applications and user data. Although availability is not directly affected, reputational damage and loss of user trust could result from successful attacks. Sectors such as government, finance, healthcare, and large enterprises that use AEM extensively are at higher risk. The vulnerability's requirement for user interaction means phishing or social engineering could be used to lure victims to malicious pages. Given the interconnected nature of European digital services, exploitation could have cascading effects on business operations and regulatory compliance, including GDPR violations.

To mitigate CVE-2025-64857, European organizations should: 1) Immediately review and apply any Adobe patches or security advisories once available. 2) Implement strict input validation on all form fields to reject or sanitize potentially malicious scripts before storage. 3) Employ robust output encoding (e.g., HTML entity encoding) when rendering user-supplied content to prevent script execution. 4) Restrict access to form submission functionalities to trusted users where possible to reduce attack surface. 5) Use Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers. 6) Conduct thorough security testing and code reviews focusing on XSS vulnerabilities in custom AEM components. 7) Educate users about the risks of interacting with suspicious links or forms. 8) Monitor web application logs for unusual input patterns or error messages indicative of attempted exploitation. 9) Consider deploying Web Application Firewalls (WAFs) with rules targeting XSS attack signatures. These steps go beyond generic advice by focusing on both prevention and detection tailored to AEM environments.