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CVE-2026-72804 – Authentication Bypass / Sensitive Information Disclosure – SiYuan before v3.7.4

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Summary

CVE-2026-72804 is an authentication bypass in SiYuan Note that allows unauthenticated (anonymous) readers to retrieve block-level content and reference topology from password-protected documents. The flaw stems from the getGraph and getLocalGraph API endpoints failing to enforce the publish-password protection tier before returning data. It is rated CRITICAL (CVSS v4.0 base score 9.2), reflecting the ease of remote, unauthenticated exploitation.

Technical details

  • Root cause: The getGraph and getLocalGraph endpoints in the SiYuan kernel do not validate whether the requested document is protected by a publish password before returning graph/content data.
  • Trigger conditions: An attacker sends unauthenticated (or reader-role) requests to these endpoints against a SiYuan instance that publishes password-protected documents.
  • Attack vector: Network — no authentication or user interaction is required, and the affected endpoints are reachable over HTTP.
  • Impact: Disclosure of block-level content and reference topology of documents that were intended to be restricted behind a publish password, resulting in unauthorized information exposure (CWE-200, CWE-862).

Affected software

  • SiYuan Note (siyuan-note/siyuan kernel, github.com/siyuan-note/siyuan/kernel), all versions up to and including v3.7.2
  • Fixed in version 3.7.4 and later

Severity

  • CVSS v3.1: 8.6 (High) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
  • CVSS v4.0: 9.2 (Critical) — 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, which adds proper password-tier validation to the getGraph and getLocalGraph endpoints.
  • If patching is not immediately possible: Restrict or block public/anonymous access to the SiYuan publish service and the getGraph/getLocalGraph API paths at the reverse proxy or network perimeter, and avoid publishing password-protected documents on internet-exposed instances until patched.

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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Map your entire attack surface (continously)

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4

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IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

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By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

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Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

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