CVE-2026-74798
Received Received - Intake

Path Traversal in SiYuan Kernel via MCP Tool

Publication date: 2026-08-17

Last updated on: 2026-08-17

Assigner: VulnCheck

Description
SiYuan kernel before v3.7.4 contains a path traversal vulnerability in the database_clean MCP tool. The tool performs only an empty-string check on the id parameter before passing it to RemoveUnusedAttributeView (kernel/model/attribute_view.go), which builds a filesystem path via filepath.Join without validating that id matches SiYuan's node-ID format. An authenticated MCP client can supply path traversal sequences in id to cause the kernel to copy an arbitrary file readable by the process into SiYuan's history directory (arbitrary file read) and then delete the original file (arbitrary file deletion). The corresponding HTTP API handler was hardened in GHSA-7hm9-v7vf-7g4w, but this MCP caller was not.

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Meta Information

Published
2026-08-17
Last Modified
2026-08-17
Generated
2026-08-17
AI Q&A
2026-08-17
EPSS Evaluated
N/A
NVD
CVE-2026-74798
EUVD
EUVD-2026-60081

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
si_yuan kernel to 3.7.4 (exc)
siyuan siyuan to 3.7.4 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

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Executive Summary

CVE-2026-74798 is a path traversal vulnerability in SiYuan's database_clean MCP tool. The tool fails to properly validate the id parameter before using it to construct filesystem paths. An attacker with authenticated MCP access can exploit this by inserting path traversal sequences into the id parameter to read arbitrary files and delete them.

Detection Guidance

To detect this vulnerability, check if SiYuan kernel versions below 3.7.4 are installed on your system. Inspect MCP tool configurations for database_clean function usage. Monitor SiYuan's history directory for unexpected file copies or deletions.

Impact Analysis

This vulnerability allows an attacker to read sensitive files on the system where SiYuan is running and delete those files. It requires authenticated MCP access, which is typically granted to AI agents for note-management tasks. Exploitation could lead to data breaches or system disruption.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles and HIPAA's security requirements. It may result in data breaches, leading to legal penalties, reputational damage, and loss of compliance certifications.

Mitigation Strategies

Upgrade SiYuan to version 3.7.4 or later immediately. Disable or restrict MCP access for untrusted clients. Review and audit file access permissions for the SiYuan process. Monitor for suspicious file operations in the history directory.

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