CVE-2026-126776

A fetched file could escape SiYuan's import directory

SiYuan · SiYuan MCP web tools on Windows

First documented disclosure · Review checkpoint

Summary

Files retrieved by MCP web tools could resolve outside the intended download path. Files writable by the SiYuan account could be created outside the import directory.

Severity and exploitation evidence

Medium · 6.0/10 · CVSS 4.0. Severity source.

Exploitation not established: The reviewed advisory does not report malicious exploitation.

Exploitation evidence source

Technical severity is not a measure of observed attacks or of risk to your deployment. Attempts, demonstrations, and successful compromise retain the qualifications in the source.

How the weakness works

Files retrieved by MCP web tools could resolve outside the intended download path.

Conditions required

A Windows user’s tool retrieved content from an attacker-controlled source.

Potential impact

Files writable by the SiYuan account could be created outside the import directory.

Affected versions and configurations

3.7.0 through versions before 3.8.10 on Windows.

Fix and mitigation status

3.8.10.

Practical next steps

Upgrade SiYuan to 3.8.10 or later on Windows.

Operating lesson

Check the authority granted to the affected component against the operation a user expects.

Evidence and limits

The public disclosure was on 2026-11-01. The CVE record was published on 2026-11-11.

Sources