Description

SiYuan versions before v3.8.2 contain a path traversal vulnerability in the reader-accessible file-read endpoint that follows symlinks when opening authorized asset paths. Attackers with reader role can request a logical asset under data/assets/ that is a symlink to a file outside the workspace and receive the target file bytes, bypassing workspace boundary restrictions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-04T12:17:20.327Z",
  "pubdate": "2026-09-04T12:17:20.327Z",
  "executiveSummary": "A path traversal vulnerability has been identified in SiYuan versions prior to v3.8.2 within the reader-accessible file-read endpoint. This security flaw allows an authenticated attacker possessing the 'reader' role to bypass workspace boundary restrictions.\nThe vulnerability manifests when the application processes requests for assets under the 'data/assets/' directory. By leveraging symbolic links (symlinks) created within this directory, an attacker can coerce the file-read endpoint to traverse outside the intended application workspace and access arbitrary files on the underlying file system with the permissions of the application process.\nThe primary risk involves unauthorized disclosure of sensitive system information, configuration files, or user data. Exploitation requires the attacker to have at least 'reader' role access to the application. This vulnerability highlights a failure in input sanitization and path validation mechanisms, as the application fails to verify if the resolved path of a requested asset remains confined within the designated root directory when following symbolic links.",
  "technicalDetails": "The root cause of this vulnerability lies in improper handling of file system symbolic links within the SiYuan file-read mechanism. The application endpoint responsible for retrieving authorized assets under the 'data/assets/' directory fails to validate the canonical path of the requested resource before performing read operations.\nIn a secure configuration, an application should resolve requested file paths to their absolute paths and verify that the resulting path starts with the expected base directory (e.g., the workspace directory). In the affected SiYuan versions, the application follows symbolic links without verifying the final target destination. An attacker can create a symlink within the 'data/assets/' folder that points to sensitive locations, such as '/etc/passwd' or other system-level configuration files.\nThe attack flow follows these steps: 1) The attacker gains or is granted 'reader' level access to the SiYuan instance. 2) The attacker identifies or creates a symlink within the 'data/assets/' logical directory path. This symlink is configured to point to a target file located outside the restricted workspace boundary. 3) The attacker triggers the file-read endpoint by requesting the path of the malicious symlink through the application's interface. 4) The server-side logic processes the request, resolving the symlink to its target, and returns the file content to the attacker. Because the server application runs with specific system privileges, it successfully accesses and reads the file contents from the target location, effectively bypassing the intended sandbox.\nThis vulnerability is particularly critical as it allows for arbitrary file reading. Depending on the environment in which SiYuan is hosted, this could lead to the exposure of application secrets, environment variables, or other sensitive user data residing on the host file system. The lack of strict path canonicalization allows for a bypass of the application's internal access controls, effectively escalating the 'reader' role's impact to include unauthorized data exfiltration."
}