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CVE-2026-74868 – Unauthenticated Brute-Force Authentication Bypass – SiYuan Note before v3.7.4

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Summary

CVE-2026-74868 is an improper restriction of excessive authentication attempts (CWE-307) affecting SiYuan Note, an open-source personal knowledge management application. The flaw lies in the Basic Auth implementation of SiYuan’s Publish Service, which lacks any rate limiting, lockout, or backoff, allowing unauthenticated remote attackers to brute-force named publish-viewer account credentials. The issue carries a HIGH severity rating and affects all versions prior to 3.7.4.

Technical details

  • Root cause: PublishServiceTransport.RoundTrip() in kernel/server/proxy/publish.go validates Basic Auth credentials for the Publish Service without any per-account failed-attempt counter, lockout, or backoff mechanism.
  • The Publish Service runs on a separate listener from the main kernel API (default TCP port 6808) and is unauthenticated-by-default at the network layer, exposing it directly to the internet in typical deployments.
  • Named "publish-viewer" accounts (Conf.Publish.Auth.Accounts) are gated only by Basic Auth credentials chosen by the operator, with no enforced minimum length or complexity.
  • Attack vector: network, no privileges and no user interaction required — an attacker can submit unlimited password guesses against known or guessed account names.
  • Impact: successful credential guessing grants unauthorized read access to published notes and notebooks (confidentiality impact only; no integrity or availability impact per the CVSS vector).

Affected software

  • SiYuan (b3log/siyuan-note), package github.com/siyuan-note/siyuan/kernel — all versions before 3.7.4
  • Fixed in version 3.7.4 and later

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 to version 3.7.4 or later, which addresses the missing throttling in the Publish Service authentication path.
  • If immediate patching is not possible: restrict network access to the Publish Service port (default 6808) to trusted IP ranges or place it behind a reverse proxy/WAF that enforces rate limiting and account lockout; ensure strong, high-entropy publish-viewer passwords are configured to raise the cost of 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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