SiYuan versions before v3.7.4 fail to enforce publish-access checks on getBlockBreadcrumb, getRefText, and getBlockTreeInfos endpoints, allowing disclosure of protected document content and metadata. Anonymous readers or publish RoleReader accounts can retrieve document titles, ancestor block content snippets, reference text, and path metadata for publish-forbidden or password-protected documents by supplying block IDs.

Affected: Go: github.com/siyuan-note/siyuan/kernel

**CVE:** This vulnerability corresponds to [CVE-2026-72805](https://nvd.nist.gov/vuln/detail/CVE-2026-72805).

### Summary

Three block endpoints return document content snippets and metadata without any publish-access check, while their sibling `getBlockInfo` which returns comparable data does enforce one. All three are `CheckAuth`-only, so they are reachable by the publish `RoleReader` token and by the anonymous account when `Publish.Auth.Enable` is `false`. An anonymous reader supplying a block ID receives content and metadata belonging to publish-forbidden and password-protected documents.

### Details

`getBlockInfo` (`kernel/api/block.go`) gates on the publish boundary: ```go if !checkBlockPublishAccess(c, id, ret) { return } ```

The following siblings in the same file perform no equivalent check:

| Endpoint | Returns | Publish check | |---|---|---| | `getBlockInfo` | root/title/path metadata | `checkBlockPublishAccess`: present | | `getBlockBreadcrumb` | `BlockPath.Name` : root document title plus every ancestor block's content snippet | none | | `getRefText` | the block's reference/anchor text (document content) | none | | `getBlockTreeInfos` | root/title/path metadata for arbitrary block IDs | none |

`getBlockBreadcrumb` returns the full ancestor chain including each ancestor block's content snippet, and `getRefText` returns block anchor text both are document content, not just metadata. `getBlockTreeInfos` returns root/title/path for any caller-supplied ID s…