Description

SiYuan versions before v3.7.4 contain a publish-boundary bypass vulnerability in WebSocket broadcast sessions that allows anonymous readers to receive unfiltered edits. Attackers can establish a WebSocket connection to the publish surface and passively receive real-time content events including password-protected and forbidden documents without authentication.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.6",
  "pubDate": "2026-08-14T12:16:43.760Z",
  "pubdate": "2026-08-14T12:16:43.760Z",
  "executiveSummary": "A publish-boundary bypass vulnerability exists in the WebSocket broadcast session mechanism within SiYuan versions prior to v3.7.4. This authorization flaw permits unauthenticated anonymous readers to intercept unfiltered real-time content modification events directly from the publish surface. The risk implications are severe, as unauthorized external actors can passively ingest sensitive textual data, including restricted, forbidden, and password-protected documents, without possessing valid session tokens or cryptographic credentials. Attackers require network access to the target deployment's WebSocket endpoint and can execute the attack passively without triggering authentication handlers. The underlying root cause stems from improper access control enforcement on real-time broadcast channels, failing to validate reader permissions against document classification policies before dispatching synchronization payloads. Consequently, this compromises the confidentiality boundary of sensitive knowledge bases hosted on vulnerable SiYuan instances.",
  "technicalDetails": "The vulnerability resides within the real-time synchronization and WebSocket broadcast architecture of SiYuan, specifically affecting versions prior to v3.7.4. The vulnerable component manages client-server message distribution for live collaborative editing and content viewing over the WebSocket protocol. The root cause is a failure in the authorization enforcement layer, which incorrectly handles access boundaries for WebSocket broadcast sessions tied to the publish surface. When clients establish a WebSocket connection, the server fails to adequately verify whether the connected entity possesses the requisite authorization or decryption privileges for restricted resources. As a result, sensitive document events bypass access control lists (ACLs). The step-by-step attack flow proceeds as follows: First, an unauthenticated attacker establishes a standard WebSocket handshake with the exposed SiYuan publish surface over the network without supplying any authentication headers, session cookies, or API tokens. Second, upon successful connection establishment, the server maps the client session to internal broadcast channels. Third, as legitimate administrative or authorized editing operations occur within the system, the application generates real-time content modification events and broadcasts them across the WebSocket channels. Fourth, the server transmits these raw, unfiltered edit payloads—encompassing password-protected and forbidden documents—directly to the unauthenticated attacker's socket. Fifth, the attacker passively reads, parses, and reconstructs the sensitive content streams in real-time. The privilege requirements for exploitation are minimal, requiring no prior authentication or administrative privileges. Network exposure is constrained only by accessibility to the instance's publication interface or WebSocket endpoint. The payload behavior involves standard JSON-formatted synchronization events that contain plaintext or lightly encoded structural document changes. The post-exploitation impact centers on a total breach of data confidentiality, allowing unauthorized enumeration and exfiltration of proprietary or confidential notes, credentials, and restricted knowledge repository assets."
}