CVE-2025-46387 is a high-severity authorization bypass vulnerability identified in Emby MediaBrowser version 4.9.0.35. The vulnerability is classified under CWE-639, which pertains to authorization bypass through user-controlled keys. In this context, the flaw allows an attacker with limited privileges (requiring some level of authentication) to manipulate user-controlled keys or tokens to bypass authorization checks within the MediaBrowser application. This bypass can lead to unauthorized access to sensitive media content or administrative functions. The vulnerability has a CVSS v3.1 base score of 8.8, indicating a high impact on confidentiality, integrity, and availability. The attack vector is network-based (AV:N), requires low attack complexity (AC:L), and only requires privileges (PR:L) but no user interaction (UI:N). The scope is unchanged (S:U), meaning the impact is contained within the vulnerable component. Successful exploitation could allow an attacker to gain unauthorized access to media files, modify or delete content, or disrupt service availability. Although no known exploits are reported in the wild yet, the vulnerability's nature and high CVSS score suggest it could be targeted by attackers once exploit code becomes available. The lack of available patches at the time of publication increases the urgency for mitigation and monitoring.

For European organizations using Emby MediaBrowser 4.9.0.35, this vulnerability poses significant risks. MediaBrowser is often deployed in corporate, educational, and media environments for streaming and managing media content. Unauthorized access could lead to exposure of confidential or proprietary media files, intellectual property theft, or leakage of sensitive user data. Integrity compromise could allow attackers to alter or delete media content, disrupting business operations or damaging reputations. Availability impact could result in denial of service to legitimate users, affecting productivity and service continuity. Given the network-based attack vector and low complexity, attackers could exploit this vulnerability remotely, increasing the threat surface. European organizations with compliance obligations under GDPR must consider the potential data breach implications and associated regulatory penalties. Additionally, sectors such as media production, broadcasting, and education, which heavily rely on media management platforms, could face operational disruptions and financial losses.

1. Immediate mitigation should include restricting access to Emby MediaBrowser instances to trusted networks and users only, using network segmentation and firewall rules to limit exposure. 2. Implement strong authentication and authorization policies, ensuring that user privileges are tightly controlled and monitored. 3. Monitor logs for unusual access patterns or attempts to manipulate user-controlled keys or tokens. 4. Disable or restrict features that allow user-controlled keys or tokens until a patch is available. 5. Engage with Emby vendor support channels to obtain updates on patch releases and apply them promptly once available. 6. Consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious authorization bypass attempts. 7. Conduct regular security assessments and penetration testing focused on authorization mechanisms within MediaBrowser deployments. 8. Educate administrators and users about the risks and signs of exploitation to enhance detection capabilities.