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CVE-2026-100635— SiYuan before v3.8.4 Authentication Bypass via Plaintext Session Cookie

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.

思岳（SiYuan）v3.8.4 之前的版本中存在一个发布服务中的身份验证绕过漏洞。在该漏洞中，会话 Cookie 在非安全的 HTTP（明文）连接下被颁发时，未设置 Secure 或 SameSite 属性。网络路径上的攻击者可以监听并通过基础认证（Basic Auth）交互获取有效的 publish-visitor-session-id Cookie，随后重放该 Cookie，从而在无需知晓账户密码的情况下访问已认证的发布接口。

CVSS 5.9 · Medium EPSS 0.26% · P16
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I. Basic Information for CVE-2026-100635

Vulnerability Information
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Vulnerability Title
SiYuan before v3.8.4 Authentication Bypass via Plaintext Session Cookie
Source: CVE Program / CVE List V5
Vulnerability Description
SiYuan before v3.8.4 contains an authentication bypass vulnerability in the publish service where session cookies are issued without Secure or SameSite attributes over plaintext HTTP connections. An on-path attacker can observe a valid publish-visitor-session-id cookie from a Basic Auth exchange and replay it to access authenticated publish endpoints without knowing the account password.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
敏感数据的明文传输
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
siyuan-note siyuan 0 ~ 3.8.4 -

II. Public POCs for CVE-2026-100635

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III. Intelligence Information for CVE-2026-100635

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Vendor Advisories for CVE-2026-100635 (1)

Other References for CVE-2026-100635 (3)

Same Patch Batch · siyuan-note · 2026-09-26 · 14 CVEs total

CVE-2026-100639 8.8 HIGH SiYuan before v3.8.4 Cross-Site Scripting via Kramdown IAL
CVE-2026-100646 8.1 HIGH SiYuan before v3.8.4 Authentication Bypass via Missing Origin Header
CVE-2026-100645 8.0 HIGH SiYuan 3.7.0 before 3.8.4 Stored XSS via Gallery Kanban
CVE-2026-100643 8.0 HIGH SiYuan before v3.8.4 Stored XSS via Attribute View textarea
CVE-2026-100641 8.0 HIGH SiYuan before v3.8.4 Stored XSS via Unescaped Flashcard Content
CVE-2026-100642 7.6 HIGH SiYuan v2.1.0 before v3.8.4 Cross-Site Request Forgery via CheckAuth
CVE-2026-100637 7.6 HIGH SiYuan before v3.8.4 Path Traversal via checkoutRepo sessionID
CVE-2026-100638 7.6 HIGH SiYuan before v3.8.4 Path Traversal via setNotebookIcon
CVE-2026-100636 7.6 HIGH SiYuan before v3.8.4 Path Traversal via exportBrowserHTML folder
CVE-2026-100644 7.5 HIGH SiYuan before v3.8.4 SQL Injection via dailyNoteSavePath
CVE-2026-100633 6.5 MEDIUM SiYuan 3.8.0 through 3.8.3 Path Traversal via MCP File Operations
CVE-2026-100634 4.7 MEDIUM SiYuan before v3.8.4 Missing Authorization via siyuan-send-windows
CVE-2026-100640 4.7 MEDIUM SiYuan before v3.8.4 Clipboard Data Disclosure via IPC

IV. Related Vulnerabilities

Same product: siyuan
Same vendor: siyuan-note
Same weakness: CWE-319

V. Comments for CVE-2026-100635

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