Which versions of SiYuan are affected by CVE-2026-68586?

A critical access control vulnerability in SiYuan versions before 3.7.3 allows unauthenticated users to retrieve private documents through direct API endpoint calls when publish Basic Authentication…. A patch is available.

Is there a public PoC exploit available for CVE-2026-68586?

Yes, a public proof-of-concept exploit is available for CVE-2026-68586. Prioritise patching immediately. EPSS: 0.2%.

How to fix or mitigate CVE-2026-68586?

Within 24 hours, inventory all SiYuan deployments and confirm current versions; immediately enable publish Basic Authentication on all instances if currently disabled. Within 7 days, stage and test the upgrade to SiYuan version 3.7.3 in a non-production environment to verify compatibility with existing data and workflows. Within 30 days, deploy version 3.7.3 to all production SiYuan instances and confirm the vulnerable API endpoints (getBacklinkDoc and getBackmentionDoc) enforce publish-access filtering.

SiYuan CVE-2026-68586

Q: What is the CVSS score of CVE-2026-68586?

CVE-2026-68586 has a CVSS 4.0 base score of 9.2 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

EUVD-2026-52274 CRITICAL

Missing Authorization (CWE-862)

2026-08-03 VulnCheck

GHSA-2mmh-4rf8-7xg6

GHSA-36v8-mpjm-8j5r

Authentication Bypass Oracle Siyuan Siyuan Note

9.2

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

9.2 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

7.5 HIGH

Network-reachable content endpoints exploitable by an anonymous publish reader when Basic Auth is off (PR:N, AC:L), yielding high confidentiality disclosure only, with no integrity or availability impact.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Aug 03, 2026 - 14:28 vuln.today

Patch available

Aug 03, 2026 - 14:02 EUVD

CVE Published

Aug 03, 2026 - 13:20 cve.org

CRITICAL 9.2

DescriptionCVE.org

SiYuan before v3.7.3 fails to apply publish-access filters to the getBacklinkDoc and getBackmentionDoc content endpoints (/api/ref/getBacklinkDoc and /api/ref/getBackmentionDoc). While the corresponding backlink list endpoints filter publish-forbidden documents, the content endpoints (gated only by CheckAuth) do not. A publish-mode reader - including an anonymous reader when publish Basic Auth is disabled - can call these endpoints directly with a publish-forbidden document's ID to retrieve its rendered DOM content and to determine whether the document references a given block (a reference-existence oracle).

AnalysisAI

Broken access control in SiYuan versions before 3.7.3 lets publish-mode readers - including anonymous users when publish Basic Auth is disabled - retrieve the rendered content of publish-forbidden documents by calling the /api/ref/getBacklinkDoc and /api/ref/getBackmentionDoc endpoints directly with a target document ID. Although the corresponding backlink list endpoints correctly filter publish-forbidden documents, these two content endpoints are gated only by CheckAuth and omit the publish-access filter, exposing DOM content and a reference-existence oracle. Reported by VulnCheck; no public exploit identified at time of analysis and not listed in CISA KEV.

Technical ContextAI

SiYuan is an open-source, self-hostable personal knowledge management / note-taking application whose 'publish' mode serves a read-only public view of a workspace while restricting certain documents from publication. The flaw is a CWE-862 Missing Authorization: the backlink and back-mention content endpoints (getBacklinkDoc, getBackmentionDoc) enforce only the generic CheckAuth session/token check but skip the publish-forbidden document filter that the sibling list endpoints apply. Because authorization is enforced inconsistently across endpoints that operate on the same document objects, an attacker can bypass the intended publish-access policy by targeting the un-filtered content endpoints directly, obtaining rendered document DOM as well as a boolean oracle indicating whether a hidden document references a specific block.

RemediationAI

Upgrade to SiYuan 3.7.3 or later, which applies the publish-access filter to the content endpoints; this is the primary and complete fix (Vendor-released patch: 3.7.3, per GHSA-36v8-mpjm-8j5r). If immediate upgrade is not possible, enable publish Basic Auth so the endpoints require credentials rather than being anonymously reachable (trade-off: all publish readers must then authenticate, reducing convenience of public sharing), and/or place the publish service behind a reverse proxy or network ACL that restricts access to /api/ref/getBacklinkDoc and /api/ref/getBackmentionDoc to trusted clients (trade-off: may break legitimate backlink rendering for public readers). As a stronger interim control, disable publish mode entirely on instances hosting sensitive publish-forbidden documents. Refer to https://github.com/siyuan-note/siyuan/security/advisories/GHSA-36v8-mpjm-8j5r for authoritative guidance.