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CVE-2026-100633: Incorrect Authorization in siyuan-note siyuan

0
High
VulnerabilityCVE-2026-100633cvecve-2026-100633
Published: 09/26/2026 (09/26/2026, 13:23:08 UTC)
Source: CVE Database V5
Vendor/Project: siyuan-note
Product: siyuan

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.

CVSS v4.0

Score 8.5high

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
High
User Interaction
None
Vuln. Confidentiality
High
Vuln. Integrity
High
Vuln. Availability
None
Subsq. Confidentiality
None
Subsq. Integrity
None
Subsq. Availability
None
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Affected software

siyuan-note

siyuan

Affected versions
>=3.8.0 <3.8.4
GitHub Actionsmore threats →ai
siyuan-note/siyuan
pkg:github/siyuan-note/siyuan
Affected versions
>=3.8.0 <3.8.4

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AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 09/26/2026, 14:04:20 UTC

Technical Analysis

SiYuan, a self-hosted personal knowledge management system, has an incorrect authorization vulnerability in versions 3.8.0 through 3.8.3. The MCP file tool's sensitive-path guard function (util.IsForbiddenAbsPath()), invoked from resolvePath(), is only applied to the root path of recursive operations and not to each resolved descendant path. This incomplete fix for a previous issue (GHSA-c8r8-95hg-mp34) allows an authenticated administrator using the in-app Agent or external MCP server to bypass the protected-workspace-file denylist. Actions such as file.grep, file.copy, and unzip can be used to access or overwrite protected descendant files without proper confirmation or restrictions. The vulnerability is resolved in version 3.8.4.

Potential Impact

An authenticated administrator can bypass protections on sensitive files and directories within the workspace, potentially exposing confidential configuration files, TLS keys, internal system files, and logs. This could lead to unauthorized disclosure or modification of sensitive data within the SiYuan environment.

Mitigation Recommendations

Upgrade SiYuan to version 3.8.4 or later, where this vulnerability is fixed. No other mitigations are indicated by the vendor advisory.

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Technical Details

Data Version
5.2
Assigner Short Name
VulnCheck
Date Reserved
2026-09-26T02:31:42.100Z
Cvss Version
4.0
State
PUBLISHED

Threat ID: 6ab7c9a5f7a7c5410652fd1c

Added to database: 09/26/2026, 13:33:25 UTC

Last enriched: 09/26/2026, 14:04:20 UTC

Last updated: 09/27/2026, 01:57:11 UTC

Views: 11

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