Which versions of SiYuan are affected by EUVD-2026-52272?

SiYuan knowledge management software (versions prior to 3.7.3) contains a critical authentication bypass that allows anonymous users to access password-protected documents, creating enterprise-wide…. A patch is available.

Is there a public PoC exploit available for EUVD-2026-52272?

Yes, a public proof-of-concept exploit is available for EUVD-2026-52272. Prioritise patching immediately. EPSS: 0.3%.

How to fix or mitigate EUVD-2026-52272?

Within 24 hours, conduct an inventory of all SiYuan deployments and identify instances running versions before v3.7.3; immediately isolate high-risk instances containing sensitive data if patching cannot be completed immediately. Within 7 days, apply the vendor-released patch to version v3.7.3 or later across all affected SiYuan instances and verify deployment completion. Within 30 days, review access logs for any signs of unauthorized API endpoint access (getHeadingChildrenDOM, getHeading*Transaction, getBacklinkDoc) and conduct a security audit of any instances that may have contained sensitive information during the vulnerable window.

SiYuan EUVD-2026-52272

Q: What is the CVSS score of EUVD-2026-52272?

EUVD-2026-52272 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: 0.3%.

| CVE-2026-68584 CRITICAL

Authentication Bypass Using an Alternate Path or Channel (CWE-288)

2026-08-03 VulnCheck

GHSA-g64v-qqpg-v37h

GHSA-7j72-f6wg-cxw6

Authentication Bypass 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

8.6 HIGH

Network-reachable, no auth or interaction, and the password authority is bypassed to disclose protected content (S:C, C:H); no integrity or availability impact.

3.1 AV:N/AC:L/PR:N/UI:N/S:C/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:H/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 versions before v3.7.3 contain an authentication bypass vulnerability in publish mode where content-returning endpoints getHeadingChildrenDOM, getHeading*Transaction, and getBacklinkDoc perform no password check despite protecting the primary getDoc endpoint. Anonymous attackers can retrieve full content of password-protected documents by obtaining internal block IDs from reader-accessible endpoints and calling unprotected content endpoints to bypass the password gate.

AnalysisAI

Authentication bypass in SiYuan (self-hosted knowledge-management/note-taking app) versions before v3.7.3 allows anonymous readers in publish mode to exfiltrate the full content of password-protected documents. While the primary getDoc endpoint enforces the publish-mode password, sibling content-returning endpoints (getHeadingChildrenDOM, the getHeading*Transaction family, and getBacklinkDoc) omit that check, so an attacker who harvests internal block IDs from reader-accessible endpoints can pull protected content directly. VulnCheck reported the issue and a vendor patch (v3.7.3) is available; there is no public exploit identified at time of analysis and it is not listed in CISA KEV.

Technical ContextAI

SiYuan is a local-first, self-hostable personal knowledge base whose backend exposes a JSON-RPC-style HTTP API. Its 'publish mode' is intended to serve selected notebooks to anonymous readers over the network while gating individual documents behind a password. The flaw is a classic CWE-288 (authentication bypass using an alternate path/channel): access control was applied to the canonical read path (getDoc) but not to functionally equivalent endpoints that also return document DOM/content - getHeadingChildrenDOM, getHeading*Transaction, and getBacklinkDoc. Because SiYuan addresses content by internal block IDs, and those IDs are discoverable through other reader-accessible endpoints (e.g., backlink and outline data), the missing check on the alternate endpoints is sufficient to reconstruct protected documents. The affected component per CPE is cpe:2.3:a:siyuan-note:siyuan (all versions prior to 3.7.3).

RemediationAI

Vendor-released patch: upgrade to SiYuan v3.7.3 or later, which adds the missing password checks to the affected content endpoints; see GHSA-7j72-f6wg-cxw6 (https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7j72-f6wg-cxw6). If immediate upgrade is not possible, disable publish mode entirely to remove the anonymous attack surface (trade-off: your published notebooks become unavailable to readers), or place the publish-mode instance behind a reverse proxy or network ACL that requires its own authentication before any endpoint is reachable (trade-off: breaks fully anonymous public sharing but preserves internal access). Do not rely on the per-document password as a boundary until patched, since the point of the flaw is that alternate endpoints ignore it; treat any content you would not publish publicly as effectively exposed on unpatched publish-mode servers.