External risk intelligence

SiYuan Authentication Bypass in Publish Mode Allows Full Content Retrieval.

CVE advisorySeverity: CRITICAL (CVSS 9.2)

CVE-2026-68584

SiYuan is a note-taking application that features a 'publish mode,' which is designed to host content publicly on the internet. Because the vulnerability exists within endpoints exposed by this public-facing publishing feature, it is commonly deployed in an internet-facing manner.

Authentication Bypass

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 in SiYuan's publishing feature could allow unauthorized access to password-protected documents. This issue stems from unprotected content endpoints that do not properly check for authentication, enabling anonymous attackers to retrieve sensitive information by bypassing password checks.

Content may be exposed publicly without passwords.
Protects sensitive information in published documents.
Confirm if published content is protected.

Attack Path

How an attacker could exploit the issue

An attacker can bypass authentication in SiYuan's publish mode to access protected documents. While the main document endpoint is secured, related content-retrieval endpoints lack password checks. By first finding internal document IDs from publicly accessible endpoints, an attacker can then use these IDs to query the unprotected endpoints and retrieve the full content of password-protected documents.

No authentication is required to begin.
Unprotected content endpoints trigger the vulnerability.
Sensitive document content can be exposed.

Live Threat

Current exploitation, exposure, and threat context

In publish mode, attackers could access and retrieve the full content of password-protected documents. This is possible when an attacker obtains internal block IDs from publicly accessible parts of the site and uses them to call endpoints that do not properly check for authentication, bypassing the password protection.

Password-protected documents.
Anonymous access to content endpoints.
Unauthorized content retrieval.

Operational Fix

Recommended remediation, mitigation, and detection steps

The SiYuan note-taking application's publish mode, when not properly configured or updated, exposes an authentication bypass vulnerability. This flaw allows unauthenticated attackers to access password-protected documents by leveraging internal block IDs. Ownership of this issue likely falls to the application owners or platform teams responsible for managing SiYuan deployments, with the initial action being to identify all instances, assess their exposure and criticality, and then coordinate remediation.

Application and platform teams own resolution.
Verify SiYuan instances and public exposure.
Plan targeted updates or access control.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is SiYuan and how is it used?

SiYuan is a privacy-first, local-first note-taking application that supports structured documents and block-based editing. Users often leverage its "publish mode" to share their notes or knowledge bases as websites. Because it is designed to manage private knowledge while offering features to host that content online for others to read, it acts as both a personal workspace and a web content server.

What does CWE-288 mean for CVE-2026-68584?

CWE-288, or Authentication Bypass Using an Alternate Path or Channel, describes a weakness where an application relies on a security check in one area but fails to enforce that same check in other parts of its code. In the context of CVE-2026-68584, while SiYuan properly guards the main document entrance with a password, it forgets to check those same credentials when handling specific internal requests for document content or children elements.

How do attackers trigger this vulnerability?

An attacker triggers this by interacting with specific content-retrieval endpoints that lack password validation. Crucially, they do not need to guess the password. They first use publicly visible endpoints to discover internal block IDs, which are like unique serial numbers for document sections. Once they have these IDs, they request the content directly through the unprotected endpoints, bypassing the security gate entirely.

Is my SiYuan instance at risk?

If you use SiYuan's publish mode to host content on the internet, your instance is at higher risk. Halo Surface Signal notes that since publish mode is designed to make content reachable globally, these instances are frequently exposed to the public internet, making them accessible to any remote attacker. If you only use SiYuan locally without enabling publish mode, this specific bypass is less relevant to your environment.

How do I secure my SiYuan deployment?

The most effective way to address this is to update your SiYuan installation to version 3.7.3 or later, which resolves the authentication oversight. Before updating, identify all your public-facing instances to confirm their current version. If you cannot update immediately, consider restricting access to your publishing endpoints through network-level controls like a VPN or firewall to prevent unauthorized external requests.

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.