GHSA-7j72-f6wg-cxw6 SiYuan: Anonymous publish-password authentication bypass via getHeadingChildrenDOM / getHeading*Transaction / getBacklinkDoc (publish mode)

• Go github.com/siyuan-note/siyuan/kernel: < 0.0.0-20260721020826-2d069dce84a2 → fixed in 0.0.0-20260721020826-2d069dce84a2

CVE: This vulnerability corresponds to CVE-2026-68584. Summary SiYuan's publish mode defines a "protected" access level: a document that is publicly listed but requires a password to read (per the product's own UI help text, protected = "Publicly visible, requires password to access"). The password is enforced on the primary content path (`getDoc`, via `FilterContentByPublishAccess`). Several other content-returning endpoints `getHeadingChildrenDOM`, `getHeadingDeleteTransaction`/`getHeadingLevelTransaction`/ `getHeadingInsertTransaction`, and `getBacklinkDoc`/`getBackmentionDoc` return rendered block DOM with no password check at all. Combined with reader-reachable endpoints that leak a protected document's internal block IDs, an anonymous reader can retrieve the full body of a password-protected document without the password. This has been reproduced end-to-end on a live instance. Details The password control and where it is enforced. Publish access has five levels encoded in `visible`/`password`/`disable`: public, protected (password), hidden, private (password), forbidden. `getDoc` correctly enforces the password for protected/private documents via `FilterContentByPublishAccess`. The bug is that other content endpoints do not. Content endpoints with no password check (all `CheckAuth`-only): • `getHeadingChildrenDOM` returns rendered DOM of a heading subtree. • `getHeadingDeleteTransaction`/`getHeadingLevelTransaction`/`getHeadingInsertTransaction` return rendered heading DOM in the computed transaction payload (no mutation occurs on this path). • `getBacklinkDoc`/`getBackmentionDoc` return rendered DOM of referencing blocks. None of these invokes the publish-password check that `getDoc` applies. Each converts a block ID into full rendered content regardless of the containing document's protected/password status. The ID-leak that removes the precondition. A protected document is, by design, publicly listed (`listDocsByPath` filters on `visible`, and protected documents are visible), so an anonymous reader obtains the document's root ID. The document's internal block/heading IDs are then obtainable from reader-reachable endpoints notably the `searchEmbedBlock` endpoint (reported separately), whose post-query filter `FilterEmbedBlocksByPublishAccess` replaces the content string but retains the block ID. So the "filtered" search still yields the protected document's internal heading IDs. (Other reader-reachable endpoints also leak block IDs, the vulnerability does not depend on any single ID source.) The chain, reproduced on a live instance. Against a real protected document (password set), an anonymous reader on port 6808 with no token and no password: 1. `getDoc(protectedDoc)` → returns the password-required placeholder (correctly blocked). 2. `searchEmbedBlock` with a statement selecting heading blocks for the document's root ID → returns the heading IDs (content filtered, IDs retained). 3. `getHeadingChildrenDOM(headingId)` → returns the full rendered body of the protected document, including its protected content. The password gate that step 1 enforces is entirely bypassed by step 3. Proof of Concept Reproduced on a local instance (SiYuan running locally, publish mode enabled on port 6808, publish Basic Auth disabled). Setup: a document marked "protected" with password, whose body contains the unique marker `TOP_SECRET_CRITICAL_123`. 1. Confirm the password gate blocks the primary path (anonymous, port 6808): ``` POST http://127.0.0.1:6808/api/filetree/getDoc {"id":"PROTECTED_DOC"} ``` Returns the password-required placeholder correctly blocked. 2. Leak the protected document's heading ID (anonymous, port 6808): ``` POST http://127.0.0.1:6808/api/search/searchEmbedBlock {"stmt":"SELECT * FROM blocks WHERE root_id='PROTECTED_DOC' AND type='h'"} ``` Returns heading blocks with their IDs; the content field is filtered but the block ID is retained. 3. Retrieve the protected content without the password (anonymous, port 6808): ``` POST http://127.0.0.1:6808/api/block/getHeadingChildrenDOM {"id":"HEADING_ID"} ``` Returns HTTP 200 with the rendered body of the protected document, including `TOP_SECRET_CRITICAL_123` retrieved with no token and no password. `getHeadingDeleteTransaction`/`getHeadingLevelTransaction`/`getHeadingInsertTransaction` and `getBacklinkDoc`/ `getBackmentionDoc` provide the same password-free content retrieval given a block ID from the protected document. Impact An anonymous reader (publish mode with auth disabled) or any publish `RoleReader` can read the full content of a password-protected published document without the password, defeating the "protected" access control the product documents as a password gate. The core defect is that these content-returning endpoints perform no publish-password check; the ID-leak endpoints (multiple sources) supply the block IDs that make the bypass reachable anonymously and untargeted. Impact is confidentiality-only (content disclosure); no modification occurs on these paths. Encrypted notebooks are out of scope. Suggested fix Apply the publish-password/publish-access check that `getDoc` uses (`FilterContentByPublishAccess`/`IsReadOnlyRoleContext` plus the password-cookie check) to every content-returning endpoint: `getHeadingChildrenDOM`, the three `getHeading*Transaction` handlers, and `getBacklinkDoc`/`getBackmentionDoc`. Separately, `FilterEmbedBlocksByPublishAccess` should omit filtered blocks entirely rather than blanking the content while retaining the ID, so that filtered results cannot be used to enumerate a protected document's internal block IDs. The durable fix is to enforce the publish boundary in the shared render/DOM path rather than per-handler, since any content endpoint that omits the check reintroduces this class.