CVE-2026-100633 (GCVE-0-2026-100633)

Vulnerability from cvelistv5 – Published: 2026-09-26 13:23 – Updated: 2026-09-26 13:23
VLAI
Title
SiYuan 3.8.0 through 3.8.3 Path Traversal via MCP File Operations
Summary
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.
Severity
8.5 (High)
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
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-863 - Incorrect Authorization
Assigner
References
Impacted products
Vendor Product Version CPE status
siyuan-note siyuan Affected: 3.8.0 , < 3.8.4 (semver)
Unaffected: 3.8.4 (semver)
    cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-09-11 00:00
Credits
dpfkdlemtp
Show details on NVD website
To clipboard 

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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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