CVE-2025-64325 is a Cross-site Scripting (XSS) vulnerability categorized under CWE-79 and CWE-116, affecting Emby Server, a personal media server application. The vulnerability exists in the Emby.Security component where the X-Emby-Client HTTP header value is incorporated into the admin dashboard's devices section without proper input neutralization or sanitization. This allows a malicious user to craft an authentication request with a manipulated X-Emby-Client header, which when viewed by an administrator on the dashboard, can execute arbitrary JavaScript code in the administrator's browser context. The attack vector is network-based (AV:N), requires low attack complexity (AC:L), no privileges (PR:L - low privileges), but does require user interaction (UI:A) as the admin must view the dashboard. The vulnerability impacts confidentiality and integrity highly (VC:H, VI:H), but does not affect availability or authentication mechanisms. The vulnerability affects Emby Server versions prior to 4.8.1.0 and Beta versions prior to 4.9.0.0-beta. The vendor has addressed the issue in these versions by implementing proper input sanitization. No known exploits have been reported in the wild as of publication. The vulnerability allows attackers to potentially hijack admin sessions, steal sensitive information, or perform unauthorized actions via script execution in the admin interface.

For European organizations using Emby Server, especially those deploying it for internal media management or as part of broader IT infrastructure, this vulnerability could lead to significant security breaches. Exploitation could allow attackers to execute malicious scripts in the context of administrative users, potentially leading to session hijacking, credential theft, or unauthorized administrative actions. This compromises the confidentiality and integrity of the system and any data accessible through the admin dashboard. Given that Emby Server is often used in small to medium enterprises and private organizations, the impact may be more pronounced in environments where administrative security practices are less stringent. Additionally, if Emby Server is exposed to untrusted networks or the internet, the risk of exploitation increases. The vulnerability could also serve as a foothold for lateral movement within networks, especially if administrators reuse credentials or if the compromised admin interface controls other critical systems.

European organizations should immediately upgrade Emby Server installations to version 4.8.1.0 or later, or Beta version 4.9.0.0-beta or later, where the vulnerability is patched. Until upgrades can be applied, organizations should restrict access to the Emby Server admin dashboard to trusted internal networks and implement network-level controls such as IP whitelisting or VPN access. Administrators should be trained to recognize suspicious activity and avoid interacting with untrusted devices or clients that could send malicious headers. Web application firewalls (WAFs) can be configured to detect and block suspicious X-Emby-Client header values containing script payloads. Regular monitoring and logging of admin dashboard access and unusual device registrations should be implemented to detect potential exploitation attempts. Finally, organizations should enforce strong authentication and session management practices to limit the impact of any successful XSS exploitation.