Description

SiYuan before v3.7.4 is missing authorization checks in 17 block metadata/content endpoints in kernel/api/block.go (including getRefText, checkBlockExist, and getBlockBreadcrumb). These handlers are gated only by basic authentication (model.CheckAuth) and lack publish-access filtering, allowing anonymous publish-mode readers to disclose private block content-derived text, structural metadata, and existence information for arbitrary block IDs across the workspace.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-18T12:19:30.643Z",
  "pubdate": "2026-08-18T12:19:30.643Z",
  "executiveSummary": "SiYuan before v3.7.4 suffers from a missing authorization vulnerability across 17 block metadata and content endpoints located in kernel/api/block.go.\nThe vulnerability allows anonymous readers operating in publish-mode to bypass intended access controls and disclose sensitive information.\nImpacted functionality includes private block content-derived text, structural metadata, and existence verification for arbitrary block IDs throughout the entire workspace.\nThe root cause stems from endpoints being gated solely by basic authentication via model.CheckAuth while entirely lacking publish-access filtering mechanisms.\nAttackers capable of accessing the network interface and operating in publish-mode can query arbitrary block identifiers without possessing appropriate privileges.\nThe risk implications involve unauthorized information disclosure of confidential workspace data, potentially exposing internal documentation structures and private content.\nMitigation requires upgrading SiYuan to version 3.7.4 or later where proper authorization and publish-access filtering controls are enforced on the affected block API endpoints.",
  "technicalDetails": "The vulnerability resides in the kernel/api/block.go component of SiYuan, specifically affecting 17 distinct block metadata and content request handlers.\nAffected functions identified within the vulnerable component include getRefText, checkBlockExist, and getBlockBreadcrumb.\nThe root cause of the flaw is an inadequate access control implementation where these specific handlers rely exclusively on basic authentication through model.CheckAuth.\nBecause the endpoints fail to implement downstream publish-access filtering, the application assumes that any caller passing the basic authentication check is authorized to access all workspace content.\nPrivilege requirements for exploitation are minimal, as anonymous publish-mode readers can successfully interact with the vulnerable endpoints.\nNetwork exposure is present wherever the SiYuan kernel API is accessible to publish-mode users or unauthenticated boundary contexts depending on the deployment configuration.\nThe step-by-step attack flow begins with an adversary identifying the target SiYuan instance running a version prior to v3.7.4.\nThe attacker crafts HTTP requests targeting the vulnerable block endpoints in kernel/api/block.go, such as requesting arbitrary block IDs via getRefText or checking block existence via checkBlockExist.\nBecause the application layer only validates basic authentication via model.CheckAuth without enforcing role-based or publish-mode content filters, the server processes the requests.\nThe application subsequently returns private block content-derived text, structural metadata, and existence confirmations back to the client.\nPost-exploitation impact includes the systematic enumeration and harvesting of private workspace blocks, allowing unauthorized extraction of sensitive notes, structural hierarchies, and relational data across the entire SiYuan workspace."
}