CVE-2025-64325 is a cross-site scripting vulnerability classified under CWE-79 and CWE-116 affecting Emby Server's web application component, specifically the Emby.Security module. The vulnerability exists because the server fails to properly neutralize input from the X-Emby-Client HTTP header during web page generation. When a malicious actor sends an authentication request with a crafted X-Emby-Client header, this value is incorporated into the devices section of the admin dashboard without adequate sanitization or encoding. This results in the injection of malicious scripts that execute in the context of the administrator's browser when they view the devices section. The vulnerability is exploitable remotely over the network (AV:N), requires low attack complexity (AC:L), no privileges (PR:L - low privileges, meaning an authenticated user with limited rights), and user interaction (UI:A) to trigger the payload. The impact on confidentiality and integrity is high due to potential session hijacking, credential theft, or further exploitation of the admin interface. Availability impact is not significant. The vulnerability affects Emby Server versions prior to 4.8.1.0 and Beta versions prior to 4.9.0.0-beta, and has been patched in these versions. No public exploits have been reported yet, but the vulnerability's nature and high CVSS score indicate a strong potential for exploitation if left unpatched.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of administrative access to Emby Server instances. Successful exploitation could allow attackers to hijack admin sessions, manipulate server configurations, or deploy further malware within the network. Media servers often store sensitive personal or organizational media content, and compromised admin access could lead to data leakage or unauthorized content distribution. Additionally, compromised servers could be leveraged as pivot points for lateral movement within corporate or home networks. The requirement for user interaction (admin viewing the devices section) means social engineering or phishing could facilitate exploitation. Given the widespread use of Emby Server in media-rich environments, organizations in Europe relying on this software for media management or streaming services could face operational disruptions and reputational damage if exploited.

1. Immediately upgrade all Emby Server instances to version 4.8.1.0 or later, or Beta 4.9.0.0-beta or later, where the vulnerability is patched. 2. Restrict access to the admin dashboard to trusted networks and users only, using network segmentation and firewall rules to limit exposure. 3. Implement web application firewall (WAF) rules that detect and block suspicious X-Emby-Client header values or unusual device registration patterns. 4. Educate administrators about the risk of interacting with untrusted device entries and encourage cautious behavior when reviewing device lists. 5. Monitor server logs for unusual authentication requests or device additions that could indicate exploitation attempts. 6. Consider deploying Content Security Policy (CSP) headers to reduce the impact of potential XSS attacks by restricting script execution sources. 7. Regularly audit and review user privileges to ensure minimal necessary access is granted, reducing the risk from compromised accounts. 8. Maintain up-to-date backups of server configurations and media content to enable recovery in case of compromise.