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CVE-2026-72810 – Unauthenticated Information Disclosure via WebSocket Broadcast Bypass – SiYuan befo

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Summary

CVE-2026-72810 is a missing-authorization vulnerability (CWE-862) in SiYuan Note that allows unauthenticated attackers to establish a WebSocket connection to the publish surface and passively receive real-time content events — including password-protected and otherwise forbidden documents — without any credentials. The issue affects all SiYuan versions prior to 3.7.4 and carries a critical severity rating.

Technical details

  • Root cause: WebSocket sessions established through the publish surface (port 6808) are added to the same broadcast session pool as authenticated sessions, and the server does not filter broadcast events by session role or authorization state.
  • Broadcast events are delivered directly over the WebSocket channel and bypass the HTTP handlers that normally enforce publish-access filters, so no authorization check is applied to them.
  • Trigger condition: an anonymous client simply opens and maintains a WebSocket connection to the exposed publish endpoint; no authentication or user interaction is required.
  • Attack vector: network-based, low attack complexity, no privileges or user interaction needed.
  • Impact: confidentiality breach — real-time exposure of workspace edits, password-protected documents, unpublished material, and other forbidden content to unauthorized parties. No direct impact on integrity or availability is reported.

Affected software

  • SiYuan Note (siyuan-note/siyuan): versions 0 up to and including 3.7.3
  • Fixed in: SiYuan Note 3.7.4 and later

Severity

  • CVSS v3.1 Base Score: 8.6 (High) — Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
  • A CVSS v4.0 score of 9.2 (Critical) has also been published for this vulnerability, with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N.

Mitigation and recommended actions

  • Immediate: Upgrade SiYuan Note to version 3.7.4 or later, where the publish surface’s WebSocket broadcast handling enforces session-level authorization.
  • If patching is not immediately possible: restrict network access to the SiYuan publish endpoint/port (e.g., 6808) to trusted networks only, disable public publishing of workspaces containing sensitive or password-protected documents, and monitor for anomalous WebSocket connections to the publish service until the upgrade can be applied.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Page title: Access Authorization - SiYuan, 思源笔记
  • Raw response body: exitSiYuan, b3log.org/siyuan

References

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