CVE-2026-116171
Deferred Deferred - Pending Action

SiYuan Path Traversal Vulnerability on Windows

Publication date: 2026-10-25

Last updated on: 2026-10-25

Assigner: VulnCheck

Description
SiYuan 3.5.4 before 3.8.7 on Windows contains a sensitive-path denylist bypass in IsSensitivePath because the Windows extended-length prefix (\\?\) survives filepath.Clean and matches no forbidden prefix. Authenticated API callers can prepend the prefix to localPath in /api/import/importStdMd to copy workspace conf files, including the API token and TLS private keys, into assets served to unauthenticated clients.

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Meta Information

Published
2026-10-25
Last Modified
2026-10-25
Generated
2026-10-25
AI Q&A
2026-10-25
EPSS Evaluated
N/A
NVD
CVE-2026-116171
EUVD
EUVD-2026-109432

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
siyuan-note siyuan 3.5.4

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

SiYuan 3.5.4 before 3.8.7 on Windows has a vulnerability where the Windows extended-length path prefix (\?\) bypasses a denylist meant to block sensitive file paths. Authenticated API users can exploit this by prepending the prefix to local file paths in the /api/import/importStdMd endpoint, allowing them to copy sensitive files like API tokens and TLS private keys into publicly accessible directories.

Detection Guidance

Check SiYuan version on Windows. If it is between 3.5.4 and 3.8.6, the system is vulnerable. Review logs for /api/import/importStdMd API calls with extended-length paths (\?\). Inspect public asset directories for unexpected conf files or tokens.

Impact Analysis

This vulnerability allows attackers with API access to expose sensitive data such as API tokens and TLS private keys by bypassing path restrictions. The exposed files could then be accessed by unauthenticated users, leading to potential data breaches or unauthorized access to the application's backend.

Compliance Impact

This vulnerability could lead to unauthorized exposure of sensitive data, violating compliance requirements under GDPR (data protection) and HIPAA (protected health information). Unauthorized access to API tokens and private keys may result in data breaches, triggering legal penalties, fines, and reputational damage for organizations handling regulated data.

Mitigation Strategies

Upgrade SiYuan to version 3.8.7 or later immediately. Disable or restrict access to the /api/import/importStdMd endpoint if possible. Review and remove any exposed API tokens or TLS keys from public directories.

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