External risk intelligence

SiYuan Unauthenticated Access to Protected Document Content

CVE advisorySeverity: CRITICAL (CVSS 9.2)

CVE-2026-72804

SiYuan is a note-taking application that supports multi-user collaboration and web publishing features. These capabilities frequently involve hosting the application as an internet-facing service or web portal to enable remote access and content sharing, making the vulnerable API endpoints accessible over the public network in many common deployment scenarios.

Information Disclosure

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability exists in SiYuan software that allows anonymous access to sensitive information within password-protected documents. This issue stems from improper validation in specific API endpoints, potentially exposing document content and structural data to unauthorized viewers. Understanding the relevance of this vulnerability to our deployed SiYuan instances is the primary concern.

Protected documents can be read without a password.
Note this issue for potential data exposure.
Confirm if our SiYuan instances are affected.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by accessing exposed `getGraph` and `getLocalGraph` endpoints. These endpoints are intended to provide information about document content and relationships but lack proper validation of the `publish-password` parameter. This allows unauthenticated users to bypass password protection and retrieve sensitive data from protected documents, as well as the complete reference topology of the system.

No authentication required.
Access exposed graph endpoints.
Read protected documents and topology.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow anonymous readers to access the block-level content of password-protected documents and view the complete reference topology of a SiYuan instance when these endpoints are accessible.

Protected document content.
Anonymous access to endpoints.
Exposure of sensitive information.

Operational Fix

Recommended remediation, mitigation, and detection steps

SiYuan's vulnerability in its `getGraph` and `getLocalGraph` endpoints requires attention from application owners and potentially infrastructure or platform teams responsible for the SiYuan deployment. The immediate first step is to identify all instances of SiYuan within the environment, determine their exposure (internal/external) and business criticality, and then locate the accountable owner for each instance to prioritize remediation.

Application owners must lead remediation efforts.
Verify external reachability and business criticality.
Plan maintenance for risk reduction.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is SiYuan?

SiYuan is a local-first, privacy-focused note-taking application. It supports collaborative editing and web publishing features, allowing users to share content via a web portal. Because it can be hosted as an internet-facing service, it often acts as a central repository for structured personal or professional information.

What does CVE-2026-72804 mean for my data?

This vulnerability involves an information exposure weakness (CWE-200). It occurs because specific API endpoints fail to verify the publish-password tier before sharing data. Essentially, the software accidentally ignores password requirements, allowing unauthorized users to read the content of protected documents and see how your notes are linked together.

How can an attacker trigger this vulnerability?

An attacker triggers this by directly accessing the getGraph or getLocalGraph endpoints of an affected SiYuan instance. Because these endpoints lack proper authentication checks, the attacker does not need to provide a password or have an existing user account to retrieve the data. Merely interacting with these endpoints is sufficient; legitimate password-protected access is not affected.

Is my SiYuan instance at risk?

If your instance is reachable over the public network, your risk is significantly higher. Halo Surface Signal indicates that because SiYuan often functions as a web-accessible portal for collaboration, these vulnerable endpoints are frequently exposed to the internet, making them easily reachable by anyone scanning for this specific flaw.

How do I secure my environment against this?

Start by identifying all SiYuan deployments in your environment and confirming their version numbers. Since this is an application-level flaw, the primary remediation is to update to version 3.7.4 or later. In the interim, assess whether you can restrict network access to the affected endpoints to limit exposure while planning your update.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.