CVE-2026-40536 in DiskStation Manager
Summary
by MITRE • 09/18/2026
An improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Audio API 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 non-sensitive information.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified as an improper limitation of a pathname to a restricted directory constitutes a classic path traversal flaw within the Audio API component of Synology DiskStation Manager versions prior to 7.2.1-69057-10, 7.2.2-72806-7, and 7.3.2-86009-2. This security defect arises from insufficient validation or sanitization of user-supplied input that is used to construct file system paths. In a typical web application architecture, the server expects specific relative paths for audio files stored within designated directories. However, due to this implementation error, an attacker can manipulate these path parameters by injecting directory traversal sequences such as dot-dot-slash characters. This manipulation allows the request to escape the intended restricted directory and access arbitrary locations on the underlying operating system file hierarchy.
From a technical perspective, the flaw resides in how the Audio API processes requests for audio resources. When a remote authenticated user submits a request containing maliciously crafted path segments, the application fails to properly canonicalize or restrict the resulting absolute path. Consequently, instead of serving only files from the authorized media directory, the server may read and return content from sensitive system directories where configuration files, logs, or other internal data are stored. This behavior bypasses the intended access control mechanisms that isolate user-specific resources from critical system components. The vulnerability is particularly dangerous because it leverages valid authentication credentials, meaning an attacker does not need to exploit a separate authentication weakness but rather abuses their existing authorized session to probe and extract information beyond their permitted scope.
The operational impact of this path traversal vulnerability centers on the unauthorized disclosure of non-sensitive information. While the description specifies that only non-sensitive data is exposed, in many enterprise environments, even seemingly benign files can provide valuable reconnaissance intelligence for further attacks. For instance, access to configuration files might reveal internal network topology, server hostnames, or application version details that aid an attacker in planning more sophisticated exploits. Additionally, exposure of log files could leak user activity patterns or error messages containing stack traces that disclose code structure and potential secondary vulnerabilities. Although the immediate risk is limited to information disclosure rather than remote code execution or privilege escalation, this capability significantly degrades the confidentiality integrity of the system by allowing authenticated users to view data they are not explicitly authorized to access.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-22, which defines Improper Limitation of a Pathname to a Restricted Directory. It also maps to MITRE ATT&CK technique T1083, specifically the File and Directory Discovery sub-technique, where adversaries explore file systems to gather information for subsequent phases of an intrusion campaign. The exploitation requires authentication, placing it within the context of post-exploitation activities or abuse of legitimate access privileges rather than initial network-based compromise.
To mitigate this vulnerability, administrators must immediately apply the vendor-provided patches by upgrading Synology DiskStation Manager to version 7.2.1-69057-10, 7.2.2-72806-7, or 7.3.2-86009-2 or later. These updates contain the necessary code corrections to enforce strict path validation and ensure that all file access requests are confined within their designated directories regardless of input content. In environments where patching is not immediately feasible, network-level controls such as web application firewalls can be configured to detect and block common directory traversal patterns in HTTP request parameters. Furthermore, implementing principle of least privilege for user accounts ensures that even if an attacker gains access through compromised credentials, their ability to traverse the file system remains limited by strict role-based access control policies. Regular security audits and input validation testing should also be conducted on custom integrations or third-party plugins interacting with the DSM API to prevent similar implementation errors in related components.