---
id: CVE-2026-73046
title: >-
  SiYuan before v3.7.4 improperly restricts excessive authentication attempts in
  the CheckAuth() middleware
summary: >-
  SiYuan before v3.7.4 improperly restricts excessive authentication attempts in
  the CheckAuth() middleware. The HTTP Basic Authentication branch, which guards
  nearly the entire /api/* surface, accepts the workspace access code
  (Conf.Acces…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-307
published: '2026-08-15'
updated: '2026-08-15'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73046'
references:
  - url: >-
      https://github.com/siyuan-note/siyuan/security/advisories/GHSA-w3xh-mmmh-r54v
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/siyuan-before-authentication-bypass-via-http-basic-auth
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-08-16T13:39:04.280Z'
epss: 0.00425
epssPercentile: 0.36454
---

## Overview

SiYuan before v3.7.4 improperly restricts excessive authentication attempts in the CheckAuth() middleware. The HTTP Basic Authentication branch, which guards nearly the entire /api/* surface, accepts the workspace access code (Conf.AccessAuthCode) as the Basic Auth password but never consults the CAPTCHA/lockout gate or increments the failure counter used by the cookie/session login path. This allows unauthenticated remote attackers to brute-force the admin access code with unlimited automated requests and obtain full RoleAdministrator access to the kernel. A secondary weakness exists because the access code is compared using a non-constant-time string comparison.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.