Description

SiYuan through 3.8.1 contains an authorization bypass vulnerability in the /api/file/getFile endpoint that allows readers to retrieve files from notebooks explicitly configured as Visible:false. Attackers with reader role can access private workspace files including notebook metadata and internal configuration by knowing the hidden notebook identifier and file path.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-04T12:17:19.640Z",
  "pubdate": "2026-09-04T12:17:19.640Z",
  "executiveSummary": "SiYuan versions up to and including 3.8.1 are affected by a critical authorization bypass vulnerability located within the /api/file/getFile endpoint. This vulnerability allows an authenticated user assigned with the reader role to circumvent access control mechanisms intended to restrict visibility of private notebooks.\nThe vulnerability resides in the application's file retrieval logic, which fails to adequately validate the authorization status of a notebook before serving file contents. By interacting directly with the /api/file/getFile endpoint, an attacker with reader-level permissions can bypass the 'Visible:false' configuration constraint.\nThe impact is significant, as it grants unauthorized access to sensitive internal data, including notebook metadata, internal system configurations, and private workspace documents. Exploitation does not require elevated administrative privileges, only a valid reader account and knowledge of the target notebook's identifier and the specific file path. The exposure of sensitive metadata and internal system files presents a high risk for information disclosure, potentially facilitating further reconnaissance or exploitation against the SiYuan instance.",
  "technicalDetails": "The vulnerability is an improper authorization flaw localized within the /api/file/getFile API handler in SiYuan through version 3.8.1. The core issue stems from the server-side logic failing to enforce access control checks when a user requests a file associated with a notebook marked with the 'Visible:false' attribute.\nUnder normal operating conditions, the application is expected to verify the requester's access rights against the notebook's visibility policy before returning the requested resource. However, in this implementation, the backend endpoint trusts the client-provided file path and notebook identifier without conducting a secondary authorization validation to ensure the authenticated session has legitimate access to that specific notebook's contents.\nThe attack flow proceeds as follows: First, an attacker authenticates as a user with the 'reader' role. Second, the attacker obtains the unique identifier for a hidden notebook and constructs a path to a specific target file within that notebook. Third, the attacker sends a request to the /api/file/getFile endpoint, supplying the known notebook ID and the path. Because the endpoint logic lacks a granular 'Visible:false' status check, the server proceeds to process the file read request regardless of the notebook's restricted state. Finally, the application serves the contents of the file directly to the attacker's session.\nThis vulnerability exposes the internal structure of the application and sensitive configuration files. By accessing notebook metadata and internal workspace configurations, an attacker can enumerate the file structure of private notebooks, potentially discovering sensitive keys, internal URLs, or confidential documentation. The exploit is deterministic and does not require complex memory corruption or bypasses for common web application defenses. The network exposure is broad, as any network-accessible SiYuan instance is vulnerable if an attacker can successfully authenticate as a reader. The lack of validation on the backend means that the file system is effectively exposed to any authenticated user capable of guessing or discovering notebook identifiers through other metadata endpoints or predictable naming conventions."
}