CVE-2026-40532 in DiskStation Manager
Summary
by MITRE • 09/18/2026
A direct request ('forced browsing') vulnerability in Wallpaper Path in Synology DiskStation Manager (DSM) before 7.2.1-69057-10, 7.2.2-72806-7 and 7.3.2-86009-2 allows remote authenticated users to obtain sensitive information.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified in Synology DiskStation Manager (DSM) versions prior to 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2 represents a critical security flaw rooted in improper access control mechanisms within the Wallpaper Path functionality. This issue is classified as a forced browsing vulnerability, which falls under the broader category of broken access controls where an application fails to properly restrict direct requests to internal resources that should not be accessible to authenticated users without specific privileges or contextual authorization. In this context, the flaw allows remote authenticated attackers to bypass intended restrictions and directly request files associated with the wallpaper configuration paths on the NAS device. The core technical deficiency lies in the web server's handling of file path inputs, where it fails to validate whether the requesting user has legitimate permission to access specific system or private directories that are exposed through this endpoint.
From a technical perspective, forced browsing exploits the tendency of web applications and servers to map URL paths directly to underlying file systems without sufficient abstraction or authorization checks at each step. When an authenticated user interacts with the DSM interface, they typically expect their session permissions to be enforced across all API endpoints and static resource requests. However, in this specific instance, the Wallpaper Path endpoint does not adequately verify if the current user context is authorized to read files from arbitrary locations on the disk storage. This oversight enables an attacker who has valid credentials for any account on the NAS to construct malicious HTTP requests targeting sensitive file paths that are normally hidden or restricted. The vulnerability essentially treats authenticated status as sufficient permission for all resource accesses, ignoring the principle of least privilege and role-based access control requirements necessary for secure system administration interfaces.
The operational impact of this vulnerability is significant due to the potential exposure of sensitive information stored on the NAS device. By leveraging forced browsing through the Wallpaper Path endpoint, an attacker can retrieve configuration files, private documents, or other data that resides in directories intended only for administrative use or specific application contexts. This disclosure compromises the confidentiality integrity of the system's data assets. Depending on the contents of the accessible paths, this could lead to further security degradation, such as gaining insights into network topology, user account structures, or cryptographic keys if they are stored in readable formats within these exposed directories. The ability to enumerate and download sensitive files undermines trust in the NAS management interface and can serve as a stepping stone for more advanced attacks, including privilege escalation or lateral movement within a connected network environment.
This vulnerability aligns with CWE-284, which describes Improper Access Control, specifically highlighting failures where access control decisions are not enforced on all resources. Furthermore, it maps to the MITRE ATT&CK technique T1083, File and Directory Discovery, as well as T1530, Data from Cloud Storage Objects, depending on how the NAS integrates with cloud services or local storage structures. The exploitation method corresponds to direct object reference manipulation where predictable or discoverable paths are used to access unauthorized data. To mitigate this risk, administrators must immediately apply the vendor-recommended patches for DSM versions 7.2.1-69057-10 and later, as well as version 7.3.2-86009-2 and later. These updates address the underlying code logic to enforce stricter access controls on the Wallpaper Path endpoint. Additionally, organizations should ensure that all DSM instances are regularly updated through automated patch management processes and monitor for any unusual file access patterns or unauthorized data exfiltration attempts via network traffic analysis tools designed to detect forced browsing activities.