SiYuan: Cross-boundary metadata disclosure via getBlockInfo (publish mode): reader-reachable document title/root info for publish-forbidden docs; sibling getDocInfo is filtered

CVE: This vulnerability corresponds to CVE-2026-68585.

Summary

The /api/block/getBlockInfo endpoint returns document root metadata including the document title (rootTitle) for a block in a publish-forbidden document, with no publish-access check. Its sibling /api/block/getDocInfo applies the publish-access filter, getBlockInfo does not. Both are gated by CheckAuth only, so getBlockInfo is reachable by the publish RoleReader token and by the anonymous account when Publish.Auth.Enable is false.

Details

The list/info side of this API is filtered while the block-info twin is not the asymmetry indicates an oversight rather than intended behavior:

getBlockInfo takes a caller-supplied block ID, validates only its format, and returns the containing document's root metadata including rootTitle (the document title) with no IsReadOnlyRoleContext / publish-access check. Because getDocInfo performs the filtering for equivalent data, the boundary is clearly meant to apply here; getBlockInfo omits it.

Proof of Concept

Reproduced on a local instance (SiYuan running locally, publish mode enabled on port 6808, publish Basic Auth disabled). Setup: a publish-forbidden document D whose title is a unique marker, containing a block BLOCKID.

1. Mark the document publish-forbidden (admin action):

POST http://127.0.0.1:6806/api/filetree/setPublishAccess
Authorization: Token <admin-token>
{"id":"DOC","visible":false,"password":"","disable":true}

2. Disclosure: the block-info endpoint returns the forbidden doc's title (anonymous, port 6808):

POST http://127.0.0.1:6808/api/block/getBlockInfo
{"id":"BLOCKID"}

Returns HTTP 200 with data.rootTitle set to the publish-forbidden document's title, along with box, path, rootID, and rootIcon. This document's title is not returned by the reader-facing filtered paths.

Impact

An anonymous reader (publish mode with auth disabled) or any publish RoleReader can read the title and root metadata (notebook, path, root ID, icon) of a publish-forbidden document by supplying a block ID from it. This discloses the existence, title, and location of documents an administrator marked as excluded from publishing.

Precondition and scope (stated honestly): the request requires a block ID from the target document; this endpoint does not enumerate arbitrary documents. The disclosure is limited to document metadata, title, notebook, path, root ID, icon — not the document body. Block IDs for forbidden documents are obtainable from other CheckAuth-only endpoints that lack the publish-access filter (reported separately). Impact is confidentiality-only, limited to metadata; no content body, no modification. Encrypted notebooks are out of scope.

Suggested fix

Apply the same publish-access check getDocInfo uses to getBlockInfo before returning root metadata, resolve the block's document and enforce IsReadOnlyRoleContext / the publish-access filter, consistent with the sibling endpoint.