EUVD-2026-57452
GHSA-f68g-4xv8-2g75
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/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
Network-accessible API requires no authentication and no user interaction; confidentiality impact is low because only tag metadata is exposed, not document content, and scope is unchanged.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
Lifecycle Timeline
2DescriptionCVE.org
SiYuan before v3.7.4 contains an information disclosure vulnerability in the /api/tag/getTag endpoint that returns tag labels and occurrence counts from password-protected documents to unauthenticated readers. Attackers can enumerate tag vocabulary and internal terminology from password-protected documents by calling the tag endpoint without providing the document's publish password.
AnalysisAI
SiYuan's /api/tag/getTag endpoint leaks tag labels and occurrence counts from password-protected documents to any unauthenticated network caller, constituting an authorization bypass under CWE-863. All SiYuan versions before 3.7.4 are affected, as confirmed by a vendor GitHub Security Advisory (GHSA-mp7r-57w4-5qm3) and the EUVD entry EUVD-2026-57452. No public exploit code has been identified and the vulnerability is not listed in the CISA KEV catalog; however, the zero-friction network exploitability (PR:N, AC:L, UI:N) means any attacker with network reach can enumerate protected document vocabulary with a single API call.
Technical ContextAI
SiYuan is a self-hosted, privacy-first knowledge management and note-taking application (CPE: cpe:2.3:a:siyuan-note:siyuan:*:*:*:*:*:*:*:*). The application implements a document-level publish-password mechanism intended to gate access to sensitive content. CWE-863 (Incorrect Authorization) is the root cause: the /api/tag/getTag endpoint performs no authorization check against the document's publish password before returning tag metadata. Because SiYuan tags serve as cross-document organizational labels - and their names can encode project codenames, medical terms, legal matter identifiers, or personal topic vocabulary - exposing tag labels and occurrence counts constitutes meaningful information disclosure even without returning document body content. The flaw is structural: a separate authorization path exists for document content but was not applied to the tag metadata API surface.
RemediationAI
Upgrade SiYuan to version 3.7.4 or later, which resolves the authorization bypass in the /api/tag/getTag endpoint per the vendor advisory at https://github.com/siyuan-note/siyuan/security/advisories/GHSA-mp7r-57w4-5qm3. If immediate upgrade is not feasible, restrict network access to the SiYuan instance by placing it behind a reverse proxy that requires authentication before any request reaches the application's API surface, or by applying firewall rules that limit access to trusted IP ranges only. Note that network-layer controls protect against external attackers but not against other users on the same local network or host who can still reach the API directly.
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Same weakness CWE-863 – Incorrect Authorization
View allSame technique Authentication Bypass
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External POC / Exploit Code
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