CVE-2026-74906: SiYuan Auth Bypass Vulnerability

CVE-2026-74906 Overview

CVE-2026-74906 is an incorrect authorization vulnerability in SiYuan, an open-source personal knowledge management application. Versions before v3.7.4 expose eight publish-mode reader-facing endpoints that filter results using the visibility list instead of the disabled list. Anonymous visitors can read content from documents explicitly marked as forbidden from publishing. The affected endpoints include search, backlink, asset content, saved criteria, recent documents, graph, and tag endpoints. The flaw is tracked under CWE-863: Incorrect Authorization.

Critical Impact
Unauthenticated network attackers can enumerate and read confidential documents that the publisher explicitly excluded from public publishing.

Affected Products

SiYuan note-taking application versions prior to v3.7.4
Deployments running SiYuan in publish mode with anonymous access enabled
Instances relying on the disabled list to restrict document visibility

Discovery Timeline

2026-08-18 - CVE-2026-74906 published to the National Vulnerability Database
2026-08-18 - Last updated in NVD database

Technical Details for CVE-2026-74906

Vulnerability Analysis

SiYuan supports a publish mode that exposes selected documents to anonymous readers over the network. Publishers can mark specific documents as disabled to prevent them from being published. Eight reader-facing endpoints incorrectly consult the visibility list rather than the disabled list when filtering results. As a result, disabled documents remain reachable through indirect discovery paths even though direct navigation is blocked.

An unauthenticated attacker can query the search endpoint, request backlinks, fetch asset content, retrieve saved search criteria, list recent documents, load the graph view, or enumerate tags. Each endpoint returns content or metadata from documents the operator intended to keep private. The confidentiality impact is high; integrity and availability are not affected.

Root Cause

The root cause is an authorization check inconsistency across the publish-mode API surface. The application maintains two independent controls: a visibility list that governs which documents are exposed in the publish UI, and a disabled list that explicitly forbids publishing. The eight affected endpoints only enforce the visibility list. Documents that were disabled but still present in the visibility set bypass the intended restriction. This matches the pattern described in CWE-863, where the software performs an authorization check using incorrect criteria.

Attack Vector

Exploitation requires network access to a SiYuan instance running in publish mode. No authentication, user interaction, or privileges are required. An attacker sends crafted HTTP requests to any of the eight affected endpoints and parses the responses to recover content from disabled documents. Full technical details are available in the GitHub Security Advisory GHSA-48p5-pffc-5r9p and the VulnCheck advisory.

No verified public proof-of-concept code is available at the time of publication. The vulnerability manifests through normal HTTP interactions with the publish-mode API and does not require specialized tooling.

Detection Methods for CVE-2026-74906

Indicators of Compromise

Anonymous HTTP requests to publish-mode endpoints for search, backlink, asset, saved criteria, recent documents, graph, and tag routes.
Unusual volume of read requests from a single source enumerating document identifiers or tags.
Access log entries containing references to document IDs known to be on the disabled list.

Detection Strategies

Review SiYuan access logs for unauthenticated queries to the eight affected publish-mode endpoints.
Correlate requested document identifiers in responses with the local disabled list to identify unauthorized disclosure.
Alert on repeated tag or backlink enumeration patterns originating from a single IP address.

Monitoring Recommendations

Place SiYuan publish-mode instances behind a reverse proxy that logs full request URIs and response sizes.
Forward web server and application logs to a centralized analytics platform for retention and query.
Monitor for outbound egress of document content in response bodies larger than expected for public documents.

How to Mitigate CVE-2026-74906

Immediate Actions Required

Upgrade SiYuan to v3.7.4 or later, which corrects the authorization check across the affected endpoints.
Audit the disabled list and confirm that no sensitive content was accessed by anonymous clients before the upgrade.
Restrict access to publish-mode instances to trusted networks until patching is complete.

Patch Information

The issue is resolved in SiYuan v3.7.4. The fix aligns the eight publish-mode reader-facing endpoints with the disabled list so that documents forbidden from publishing are no longer returned. Refer to the GitHub Security Advisory GHSA-48p5-pffc-5r9p for the fix commit and release notes.

Workarounds

Disable publish mode entirely until the instance is upgraded to v3.7.4.
Place SiYuan behind an authenticating reverse proxy that requires credentials for all endpoints.
Remove sensitive documents from the SiYuan workspace or export them to an isolated instance until the patch is applied.

bash

# Configuration example: restrict publish-mode access with an authenticating reverse proxy
# nginx snippet requiring basic auth for the SiYuan publish endpoints
location / {
    auth_basic "SiYuan Publish";
    auth_basic_user_file /etc/nginx/.siyuan_htpasswd;
    proxy_pass http://127.0.0.1:6806;
}