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CVE-2026-72809— SiYuan before v3.7.4 Authentication Bypass via Localhost Trust

Quick assessment

Affected
siyuan-note siyuan
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

SiYuan是SiYuan团队开源的一款文档管理软件。 SiYuan 3.7.2及之前版本存在授权问题漏洞，该漏洞源于内核的CheckAuth函数存在身份验证绕过漏洞，对特定端点中RemoteAddr为回环地址（127.0.0.1）的任意请求授予管理员角色，可能导致远程未认证攻击者获得管理员访问权限。

CVSS 8.0 · High EPSS 0.30% · P21

Affected Version Matrix 2

VendorProduct Version RangeStatus
siyuan-note siyuan < 3.7.4 affected
3.7.4 unaffected
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I. Basic Information for CVE-2026-72809

Vulnerability Information
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Vulnerability Title
SiYuan before v3.7.4 Authentication Bypass via Localhost Trust
Source: CVE Program / CVE List V5
Vulnerability Description
SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
使用欺骗进行的认证绕过
Source: CVE Program / CVE List V5
Vulnerability Title
SiYuan 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
SiYuan是SiYuan团队开源的一款文档管理软件。 SiYuan 3.7.2及之前版本存在授权问题漏洞，该漏洞源于内核的CheckAuth函数存在身份验证绕过漏洞，对特定端点中RemoteAddr为回环地址（127.0.0.1）的任意请求授予管理员角色，可能导致远程未认证攻击者获得管理员访问权限。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
siyuan-note siyuan 0 ~ 3.7.4 -

II. Public POCs for CVE-2026-72809

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III. Intelligence Information for CVE-2026-72809

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Vendor Advisories for CVE-2026-72809 (1)

Other References for CVE-2026-72809 (1)

Same Patch Batch · siyuan-note · 2026-08-12 · 22 CVEs total

CVE-2026-72793 8.6 HIGH SiYuan before v3.7.4 Information Disclosure via /api/system/getConf
CVE-2026-72804 8.6 HIGH SiYuan before v3.7.4 Authentication Bypass via Graph Endpoints
CVE-2026-72789 8.6 HIGH SiYuan before v3.7.4 Authentication Bypass via Encrypted Notebooks
CVE-2026-72798 8.6 HIGH SiYuan before v3.7.4 Information Disclosure via renderAttributeView
CVE-2026-72794 8.6 HIGH siyuan before v3.7.4 Session Cookie Key Disclosure via getConf
CVE-2026-72795 8.6 HIGH SiYuan before v3.7.4 Information Disclosure via Embed Block
CVE-2026-72807 8.0 HIGH SiYuan before v3.7.4 SQL Injection via queryBlocks template
CVE-2026-72801 7.5 HIGH SiYuan before v3.7.4 Information Disclosure via Encryption Key Material
CVE-2026-72796 5.8 MEDIUM SiYuan before v3.7.4 Access Control Bypass via Static Routes
CVE-2026-72806 5.8 MEDIUM SiYuan before v3.7.4 Authentication Bypass via Attribute View
CVE-2026-72791 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via getAttributeViewFieldViews
CVE-2026-72788 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via UILayout Filter
CVE-2026-72805 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via Block Endpoints
CVE-2026-72803 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via getBlockAttrs
CVE-2026-72790 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via getNotebookInfo
CVE-2026-72808 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via getFileAnnotation
CVE-2026-72797 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via getEncryptedNotebookStatus
CVE-2026-72792 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via Tag API
CVE-2026-72799 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via Path Resolution
CVE-2026-72800 5.8 MEDIUM SiYuan before v3.7.4 Information Disclosure via Unfiltered API

Showing top 20 of 22 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: siyuan
Same vendor: siyuan-note
Same weakness: CWE-290

V. Comments for CVE-2026-72809

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