Description

SiYuan before v3.7.4 fails to properly validate publish access for encrypted notebooks, treating them as publicly accessible by default. Anonymous readers can enumerate and retrieve fully decrypted document content from unlocked encrypted notebooks through the publish API without authentication or key material.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.6",
  "pubDate": "2026-08-12T20:17:50.270Z",
  "pubdate": "2026-08-12T20:17:50.270Z",
  "executiveSummary": "A critical authorization bypass vulnerability exists in SiYuan prior to v3.7.4, specifically involving the improper validation of publish access controls for encrypted notebooks. The root cause stems from the application treating encrypted notebooks as publicly accessible by default within the publishing mechanism, rather than enforcing strict cryptographic or role-based access checks. This security flaw allows unauthenticated remote attackers and anonymous readers to completely bypass confidentiality controls protecting sensitive user data. The impact includes the unauthorized enumeration and retrieval of fully decrypted document content originating from unlocked encrypted notebooks. Attackers require no prior authentication, valid session tokens, or cryptographic key material to successfully interact with the vulnerable publish API endpoints. Consequently, the risk implication is severe, as sensitive personal or proprietary notes hosted on instances running affected versions are exposed directly to the public internet. Exploitation is trivial, requiring only direct HTTP interactions with the exposed publish API interface of a vulnerable SiYuan server hosting an encrypted workspace, making remediation through software updates urgent.",
  "technicalDetails": "The vulnerability resides within the publishing subsystem of SiYuan, specifically affecting versions prior to v3.7.4. The vulnerable component is responsible for handling API requests directed at published notebook contents. The core root cause is an inadequate access control validation logic within the publish API routing and controller layers. When a notebook is designated as encrypted, the application logic fails to properly verify whether a requesting entity possesses the necessary authorization parameters or decryption keys before serving the content. Instead, the backend implementation incorrectly defaults to treating these sensitive notebooks as publicly accessible resources.\nFrom an attack flow perspective, exploitation requires network exposure of the SiYuan instance running an affected version. An unauthenticated attacker initiates the attack by interacting directly with the publish API endpoints exposed over the network. Because the application lacks proper privilege requirements and authentication checks for this specific codepath, the attacker does not need to provide session cookies, authorization headers, or the cryptographic keying material normally required to unlock the encrypted notebook. \nUpon receiving the crafted request, the vulnerable publish API processes the query against the internal document repository. The backend service retrieves the requested document data, and due to the missing validation checks, handles the underlying encrypted content without enforcing access restrictions. In scenarios where the targeted encrypted notebook is already in an unlocked state within the server's memory or context, the application serves the fully decrypted document payload back to the requester. The payload behavior consists of plaintext JSON or rendered document content containing sensitive notes and hierarchical data. The post-exploitation impact allows an external, unauthenticated malicious actor to systematically enumerate workspace structures and harvest all decrypted document contents, leading to a complete compromise of data confidentiality."
}