CVE-2026-72805: SiYuan Missing Publish-access Check On GetBlockBreadcrumb, Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-67x2-mq63-v9vm",
  "modified" : "2026-09-03T22:52:12Z",
  "published" : "2026-09-03T22:52:12Z",
  "aliases" : [ "CVE-2026-72805" ],
  "summary" : "SiYuan: Missing publish-access check on getBlockBreadcrumb, getRefText, and getBlockTreeInfos discloses content and metadata of protected/forbidden documents",
  "details" : "**CVE:** This vulnerability corresponds to [CVE-2026-72805](https://nvd.nist.gov/vuln/detail/CVE-2026-72805).\n\n### Summary\n\nThree 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.\n\n### Details\n\n`getBlockInfo` (`kernel/api/block.go`) gates on the publish boundary:\n```go\nif !checkBlockPublishAccess(c, id, ret) {\n    return\n}\n```\n\nThe following siblings in the same file perform no equivalent check:\n\n| Endpoint | Returns | Publish check |\n|---|---|---|\n| `getBlockInfo` | root/title/path metadata | `checkBlockPublishAccess`: present |\n| `getBlockBreadcrumb` | `BlockPath.Name` : root document title plus every ancestor block's content snippet | none |\n| `getRefText` | the block's reference/anchor text (document content) | none |\n| `getBlockTreeInfos` | root/title/path metadata for arbitrary block IDs | none |\n\n`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 set via `model.GetBlockTreeInfosInBox(...)` with no gate.\n\n`getBlockBreadcrumb` and `getRefText` additionally accept a client-supplied notebook argument that routes to the `*InBox` variants, so the same unguarded path applies to encrypted-notebook reads while the notebook is unlocked.\n\nThe correct primitive already exists in the codebase and is used by `getBlockInfo`; these three handlers simply do not call it.\n\n### Proof of Concept\n\nPrecondition: publish mode enabled (default port 6808); anonymous when `Publish.Auth.Enable` is `false`, otherwise any publish reader account. A document `D` is marked publish-forbidden (or password-protected) and contains a block `BLOCK_ID` under a heading with distinctive content.\n\n**Control: the gated sibling correctly refuses:**\n```\nPOST http://127.0.0.1:6808/api/block/getBlockInfo\n{\"id\":\"BLOCK_ID\"}\n```\nBlocked by `checkBlockPublishAccess`.\n\n**Disclosure: the ungated siblings return the data anyway:**\n```\nPOST http://127.0.0.1:6808/api/block/getBlockBreadcrumb\n{\"id\":\"BLOCK_ID\"}\n→ ancestor chain including the forbidden document's title and ancestor block content snippets\n\nPOST http://127.0.0.1:6808/api/block/getRefText\n{\"id\":\"BLOCK_ID\"}\n→ the block's reference/anchor text (content of the forbidden document)\n\nPOST http://127.0.0.1:6808/api/block/getBlockTreeInfos\n{\"ids\":[\"BLOCK_ID\"]}\n→ root ID, title, and path for the forbidden document\n```\n\nVerified by code inspection at `origin/master` (`eef10568`): `getBlockInfo` contains the `checkBlockPublishAccess` call; `getBlockBreadcrumb`, `getRefText`, and `getBlockTreeInfos` contain no publish-access, publish-ignore, or readonly-role check in their bodies.\n\n### Impact\n\nAn anonymous reader (publish mode with auth disabled) or any publish `RoleReader` can read, for documents explicitly excluded from publishing or protected by a publish password:\n- the document title and full ancestor chain, including ancestor block content snippets (`getBlockBreadcrumb`);\n- block reference/anchor text, i.e. document content (`getRefText`);\n- root ID, title, and path metadata for arbitrary block IDs (`getBlockTreeInfos`).\n\nBecause `getBlockBreadcrumb` and `getRefText` accept a notebook argument routing to the `*InBox` variants, the same disclosure applies to encrypted notebooks while unlocked. Confidentiality-only; the precondition is a block ID, obtainable from other reader-reachable endpoints.\n\n### Suggested fix\n\nCall `checkBlockPublishAccess` (as `getBlockInfo` does) in `getBlockBreadcrumb`, `getRefText`, and `getBlockTreeInfos` before returning data for `getBlockTreeInfos`, apply it per ID and drop unauthorized entries. Confirm the `*InBox` variants (`GetBlockRefTextInBox`, `BuildBlockBreadcrumbInBox`) enforce the same boundary so the notebook-argument path is covered.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/siyuan-note/siyuan/kernel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.0.0-20260723163028-931ba693375e"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-67x2-mq63-v9vm"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-72805"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/commit/931ba693375ea9877b2ef74f9bfb632fad5bab3f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/siyuan-note/siyuan"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/siyuan-before-information-disclosure-via-block-endpoints"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-862" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-03T22:52:12Z",
    "nvd_published_at" : null
  }
}