SiYuan: Missing publish-access filter on getBlockAttrs and batchGetBlockAttrs discloses block attributes (name, alias, memo, custom fields) of protected documents

CVE: This vulnerability corresponds to CVE-2026-72803.

Summary

POST /api/attr/getBlockAttrs and POST /api/attr/batchGetBlockAttrs return a block's full attribute set (IAL) with no publish-access check. Both 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 the block's name, alias, memo, bookmark, tags, and every custom-* attribute including for blocks in publish-forbidden and password-protected documents. The batch variant accepts an ID list, making it a bulk extraction primitive.

Details

Neither handler applies a filter:

// /api/attr/getBlockAttrs      (router line 301)
ret.Data = sql.GetBlockAttrs(id)

// /api/attr/batchGetBlockAttrs (router line 302)
ret.Data = sql.BatchGetBlockAttrs(idList)

sql.GetBlockAttrs is a direct database read returning the block's entire IAL: name, alias, memo, bookmark, tags, and any custom-* key/value the user has set. Several of these are user-authored free text memos in particular are freeform notes attached to a block so this is document content, not merely structural metadata.

batchGetBlockAttrs takes an arbitrary list of block IDs in a single request, so an attacker holding a set of block IDs can sweep attributes across the entire workspace in one call.

Guarded-sibling asymmetry. The sibling metadata endpoint getBlockInfo calls checkBlockPublishAccess(c, id, ret) before returning; getBlockAttrs and batchGetBlockAttrs call nothing.

Verified at origin/master: both handler bodies contain no publish-access, publish-ignore, or readonly-role check, and both routes are registered CheckAuth without CheckAdminRole.

Proof of Concept

Precondition: publish mode enabled (default port 6808); anonymous when Publish.Auth.Enable is false, otherwise any publish reader account. A document is marked publish-forbidden (or password-protected) and contains a block with a memo and a custom attribute set.

Single-block disclosure:

POST http://127.0.0.1:6808/api/attr/getBlockAttrs
{"id":"<BLOCK_ID_IN_PROTECTED_DOC>"}

Returns the block's IAL: name, alias, memo, bookmark, tags, and all custom-* values.

Bulk disclosure:

POST http://127.0.0.1:6808/api/attr/batchGetBlockAttrs
{"ids":["<ID1>","<ID2>","<ID3>"]}

Returns the attribute sets for every supplied ID in one response, with no per-ID authorization.

Control: the sibling getBlockInfo with the same block ID is refused by checkBlockPublishAccess, confirming the boundary is enforced elsewhere and omitted here.

Impact

An anonymous reader (publish mode with auth disabled) or any publish RoleReader can read block attributes belonging to publish-forbidden and password-protected documents, including user-authored memos and arbitrary custom-* values. The batch endpoint turns this into a bulk primitive: given a set of block IDs, an attacker retrieves attributes across the whole workspace in a single request. Confidentiality-only.

Suggested fix

Call checkBlockPublishAccess in getBlockAttrs before returning, matching getBlockInfo. For batchGetBlockAttrs, apply the check per ID and drop unauthorized entries from the response rather than failing the whole batch.