CVE-2025-46390 is a high-severity vulnerability identified in Emby MediaBrowser version 4.9.0.35, classified under CWE-204: Observable Response Discrepancy. This type of vulnerability arises when an application provides different responses based on certain inputs or conditions, allowing an attacker to infer sensitive information indirectly by observing these discrepancies. In this case, the vulnerability allows an unauthenticated remote attacker to send network requests (as indicated by CVSS vector AV:N/AC:L/PR:N/UI:N) and observe differences in the application's responses that reveal confidential information. The CVSS score of 7.5 reflects a high impact on confidentiality (C:H), with no impact on integrity or availability. The vulnerability does not require any privileges or user interaction, making it easier to exploit remotely over the network. Although no known exploits are currently reported in the wild, the lack of authentication and the direct network attack vector make this a significant risk. Emby MediaBrowser is a media server software used to organize, stream, and share media content across devices. The observable response discrepancy could allow attackers to enumerate user accounts, media libraries, or other sensitive configuration details, potentially facilitating further targeted attacks or privacy violations. No patches or fixes are currently linked, indicating that users of the affected version remain vulnerable until an update is released and applied.

For European organizations using Emby MediaBrowser, this vulnerability poses a notable risk to confidentiality of media content and user data. Media servers often contain personal or corporate multimedia files, and unauthorized disclosure could lead to privacy breaches or intellectual property exposure. In sectors such as media production, education, or corporate environments where Emby is deployed, attackers could leverage this vulnerability to gather sensitive information without authentication, potentially escalating to further attacks. The lack of impact on integrity and availability means systems may continue to operate normally, making detection harder. Given the remote and unauthenticated nature of the exploit, attackers could scan for vulnerable Emby instances across European networks, increasing the risk of widespread information leakage. This could also affect compliance with European data protection regulations such as GDPR, as unauthorized disclosure of personal data could lead to legal and financial consequences.

European organizations should immediately identify any deployments of Emby MediaBrowser version 4.9.0.35 and restrict external network access to these servers using firewalls or network segmentation to limit exposure. Since no patches are currently available, applying strict access controls and monitoring network traffic for unusual requests targeting Emby services is critical. Organizations should consider disabling or limiting Emby’s network-facing interfaces until a vendor patch is released. Employing Web Application Firewalls (WAFs) with custom rules to detect and block anomalous request patterns that could exploit response discrepancies can provide additional protection. Regularly auditing logs for signs of reconnaissance or probing activity targeting Emby servers is recommended. Once a patch is released, prompt testing and deployment are essential. Additionally, organizations should review their media server usage policies and consider alternative solutions with stronger security postures if immediate mitigation is not feasible.