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CVE-2026-100633— SiYuan 3.8.0 through 3.8.3 Path Traversal via MCP File Operations

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.

思源笔记（SiYuan）是一款自托管的个人知识管理系统。在 3.8.0 至 3.8.3 版本中，MCP 文件工具中的敏感路径防护机制（util.IsForbiddenAbsPath()，由 resolvePath() 调用）仅对递归操作的允许根目录生效，而未对每个解析出的子路径进行检查——这是针对 GHSA-c8r8-95hg-mp34 的修复不彻底。 因此，经身份验证的管理员可以通过应用内代理（Agent）或外部 MCP 服务器绕过受保护工作区文件的拒绝列表： 可从非隐藏的受保护子路径（例如 conf/conf.

CVSS 6.5 · Medium EPSS 0.33% · P23
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I. Basic Information for CVE-2026-100633

Vulnerability Information
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Vulnerability Title
SiYuan 3.8.0 through 3.8.3 Path Traversal via MCP File Operations
Source: CVE Program / CVE List V5
Vulnerability Description
SiYuan is a self-hosted personal knowledge management system. In versions 3.8.0 through 3.8.3, the MCP file tool's sensitive-path guard (util.IsForbiddenAbsPath(), invoked from resolvePath()) is applied only to the allowed root of recursive operations and not to each resolved descendant path — an incomplete fix for GHSA-c8r8-95hg-mp34. An authenticated administrator using the in-app Agent or the external MCP server can therefore bypass the protected-workspace-file denylist: file.grep can return matching lines from non-hidden protected descendants (for example conf/conf.json, TLS keys, data/snippets/conf.json, data/templates/, data/.siyuan/publishAccess.json, notebook .siyuan internals, or the kernel log), file.copy can copy protected descendants to an ordinary path where file.read can then retrieve them, and unzip can overwrite protected descendants using ordinary, lexically contained ZIP member names. Because file.grep is globally classified as a safe action, it receives no per-call confirmation, and the confirmation cards for file.copy and unzip show only the allowed root arguments. This issue is fixed in version 3.8.4. Suggested title: SiYuan 3.8.0 through 3.8.3 Sensitive-Path Guard Bypass in Recursive MCP File Operations.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
siyuan-note siyuan 3.8.0 ~ 3.8.4 -

II. Public POCs for CVE-2026-100633

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III. Intelligence Information for CVE-2026-100633

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Vendor Advisories for CVE-2026-100633 (1)

Other References for CVE-2026-100633 (1)

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-2026-100635 5.9 MEDIUM SiYuan before v3.8.4 Authentication Bypass via Plaintext Session Cookie
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-863

V. Comments for CVE-2026-100633

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