SiYuan: Full-content disclosure of publish-disabled documents via getHeading*Transaction endpoints (publish mode): reader-reachable rendered DOM with no publish-access check

CVE: This vulnerability corresponds to CVE-2026-68587.

Summary

Three "heading transaction" endpoints /api/block/getHeadingDeleteTransaction, /api/block/getHeadingLevelTransaction, and /api/block/getHeadingInsertTransaction return the rendered block DOM of a heading and its subtree in the computed transaction payload, with no publish-access check. They are gated by CheckAuth only, so they are reachable by the publish RoleReader token, and by the anonymous account when Publish.Auth.Enable is false.

Despite their write-implying names, these endpoints perform no mutation on this path, they compute a transaction object and return it, and that object contains RenderNodeBlockDOM output. As a result, an anonymous reader who supplies a heading block ID can read the full rendered content of a document that has been explicitly marked publish-disabled by an administrator, content that the reader-facing /api/filetree/getDoc path correctly refuses to return.

Details

Route / auth tier. All three routes are registered CheckAuth-only (no CheckAdminRole). CheckAuth admits RoleReader, and the publish proxy forwards port-6808 traffic with a Reader JWT (anonymous account when publish auth is disabled). Anonymous/reader reachable.

No publish-access filter. GetHeadingDeleteTransaction / GetHeadingLevelTransaction / GetHeadingInsertTransaction load the heading's block tree and render its DOM into the returned transaction's operation data. None of the three invokes IsReadOnlyRoleContext / the publish-access filter that the reader-safe content path (getDoc) applies. The reader-facing content endpoints (getDoc, and the CheckAdminRole-gated getBlockDOM/getBlockKramdown) treat rendered block DOM as gated content; these three transaction endpoints return the same rendered DOM without that gate.

Write-implying name, read behavior. On this code path the endpoints only compute the transaction (e.g. the undoOperations a delete would produce) and return it; nothing is deleted or modified. The returned operation data includes the rendered HTML of the heading subtree. This mismatch, mutation-shaped name, content-returning behavior is why the gap is easy to miss.

Proof of Concept

Reproduced on a local instance (SiYuan running locally, publish mode enabled on port 6808, publish Basic Auth disabled). DOC is a document containing a heading HEADING whose body contains the unique marker UNIQUE_MARKER_99, and DOC is marked publish-disabled by the administrator.

1. Confirm the document is publish-disabled (admin action, the boundary that should block reads):

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

2. Baseline: the reader-safe content path correctly blocks it (anonymous, port 6808):

POST http://127.0.0.1:6808/api/filetree/getDoc
{"id":"DOC"}

Returns the blocked/placeholder response, the publish filter is applied, no content.

3. Disclosure: the transaction endpoint returns the content (anonymous, port 6808):

POST http://127.0.0.1:6808/api/block/getHeadingDeleteTransaction
{"id":"HEADING"}

Returns HTTP 200; data.undoOperations[].data contains the rendered HTML of the heading subtree, including the hidden body text UNIQUE_MARKER_99. Nothing is deleted — the endpoint only computes the transaction. This is the full content of a publish-disabled document returned to an anonymous reader.

4. Sibling endpoints: same disclosure, same input:

POST http://127.0.0.1:6808/api/block/getHeadingLevelTransaction
{"id":"HEADING","level":2}

POST http://127.0.0.1:6808/api/block/getHeadingInsertTransaction
{"id":"HEADING"}

Both return the rendered DOM of the heading subtree in their operation data.

Impact

An anonymous reader (publish mode with auth disabled) or any publish RoleReader who supplies a heading block ID can read the full rendered content of a publish-disabled document, defeating a boundary the administrator explicitly configured.

Precondition: the request requires the target heading's block ID. Block IDs are high-entropy and are not returned by this endpoint, so this endpoint alone does not permit untargeted enumeration of arbitrary documents. However, block/heading IDs for publish-disabled documents are obtainable from other CheckAuth-only endpoints that lack the publish-access filter (the publish-boundary handler set reported separately, e.g. getHeadingChildrenIDs). Chained with such an ID source, this yields end-to-end unauthenticated full-content disclosure of publish-disabled documents. Presented standalone, the attacker must already possess the heading ID.

Impact is confidentiality-only: these endpoints return content but do not (on this path) modify data. No admin role, CSRF token, or write permission is required. Encrypted notebooks are out of scope.

Suggested fix

Apply the same publish-access check the content path uses IsReadOnlyRoleContext / the publish-access filter used by getDoc to all three getHeading*Transaction handlers, or gate them behind CheckAdminRole consistent with getBlockDOM/getBlockKramdown. Any endpoint that returns rendered block DOM should enforce the same publish boundary as the primary content path.