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CVE-2026-72801 – Information Disclosure / Offline Password Cracking – SiYuan Note before v3.7.4

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Summary

CVE-2026-72801 is an information disclosure vulnerability in SiYuan Note, a personal knowledge management application, affecting all versions before v3.7.4. Two unauthenticated API endpoints exposed in "publish mode" leak encrypted-notebook key-derivation material and wrapped data encryption keys, letting an attacker perform unlimited offline password-cracking attempts against a notebook’s master password. The vulnerability is rated HIGH severity (CVSS 8.7).

Technical details

  • Root cause: POST /api/system/getConf returns the NotebookCrypto configuration object, including the Argon2id salt, KDF cost parameters, and a password verifier. The server-side HideConfSecret() redaction routine, which strips other sensitive configuration fields, does not reference or redact NotebookCrypto.
  • A second endpoint, POST /api/notebook/getNotebookConf, returns the wrapped per-notebook data encryption key (WrappedDEK) with no reader-level (publish role) access filtering.
  • Trigger conditions: the target instance must be running in publish mode with at least one encrypted notebook; no authentication or special privileges are required to reach either endpoint.
  • Attack vector: network — an unauthenticated remote attacker sends requests to the two endpoints and harvests the returned cryptographic material.
  • Impact: the leaked salt, KDF parameters, verifier, and wrapped keys allow GPU-accelerated, rate-limit-free offline brute-forcing of the notebook master password, ultimately exposing the confidentiality of encrypted notebook contents. Integrity and availability are not affected.

Affected software

  • SiYuan (siyuan-note/siyuan), golang package github.com/siyuan-note/siyuan/kernel
  • All versions prior to v3.7.4 running in publish mode

Severity

  • CVSS v4.0: 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
  • CVSS v3.1: 7.5 (HIGH) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Mitigation and recommended actions

  • Immediate: upgrade SiYuan to v3.7.4 or later, which removes NotebookCrypto from the unauthenticated getConf response and applies reader-level filtering to getNotebookConf.
  • If patching is not immediately possible: disable publish mode for workspaces containing encrypted notebooks, or restrict network access to the publish endpoints to trusted/authenticated sources only.
  • After upgrading, consider rotating master passwords for any notebooks that were exposed in publish mode prior to the fix, since previously disclosed key-derivation material could still be brute-forced offline.

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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