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CVE-2026-73045 – Unauthenticated Brute-Force of Publish Passwords – SiYuan Note before v3.7.4

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Summary

CVE-2026-73045 is an improper restriction of excessive authentication attempts vulnerability (CWE-307) affecting SiYuan Note prior to version 3.7.4. The authFilePublishAccess endpoint, which validates the password for a password-protected "Publish" notebook, imposes no rate limiting, attempt counter, or CAPTCHA, allowing an unauthenticated remote attacker to brute-force a notebook’s publish password. The issue carries a CVSS v4.0 score of 8.7 (High).

Technical details

  • Root cause: the POST /api/filetree/authFilePublishAccess endpoint (kernel/api/filetree.go) accepts unlimited password-guess attempts with no throttling, lockout, or CAPTCHA challenge.
  • The password check is additionally implemented as a plain string comparison rather than a constant-time comparison, introducing a secondary observable timing discrepancy (CWE-208).
  • Trigger conditions: a notebook must be published via SiYuan’s "Publish" feature and protected with a password; no authentication, privileges, or user interaction are required to attack the endpoint.
  • Attack vector: network — the endpoint is intentionally exposed to unauthenticated callers by design, since it exists to gate public access to published notebooks.
  • Impact: successful brute-forcing exposes the confidentiality of the targeted published notebook’s content. Impact is scoped to the individual notebook and does not grant broader workspace or administrative access.

Affected software

  • SiYuan Note: all versions prior to 3.7.3 (inclusive) — i.e., all versions before 3.7.4.

Severity

  • CVSS v3.1 Base Score: 7.5 (High) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
  • CVSS v4.0 Base Score: 8.7 (High) — CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Mitigation and recommended actions

  • Immediate: upgrade SiYuan Note to version 3.7.4 or later, which implements rate limiting and secure password validation on the publish-access endpoint.
  • If patching is not immediately possible: avoid password-protecting published notebooks containing sensitive content until upgraded, or restrict network access to the SiYuan instance (e.g., via VPN, IP allow-listing, or a reverse proxy with rate limiting) to reduce exposure to brute-force attempts.

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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