CVE-2026-67342

About 14 HTTP handlers resolve the {database} path param and call getDatabase(...) WITHOUT user.canAccessToDatabase(...) and without setting the engine principal, because they extend AbstractServerHttpHandler directly instead of DatabaseAbstractHandler (which holds the only per-database gate at DatabaseAbstractHandler.java:69,88-90). Affected: PostBatchHandler:129, PostTimeSeriesWriteHandler:115, PostPrometheusWriteHandler:83, PostTimeSeriesQueryHandler:69, GetTimeSeriesLatestHandler:58, PostGrafanaQueryHandler:69, GetGrafanaHealthHandler:49, GetGrafanaMetadataHandler:52, GetPromQLQueryHandler:63, GetPromQLQueryRangeHandler:71, GetPromQLLabelsHandler:56, GetPromQLLabelValuesHandler:62, GetPromQLSeriesHandler:72, PostPrometheusReadHandler:85. The engine fallback is also void: LocalDatabase.checkPermissionsOnDatabase:711 early-returns when getCurrentUser()==null.

Exploit: a user authorized only for DB 'a' calls POST /api/v1/batch/b, POST /api/v1/ts/b/write, GET /api/v1/ts/b/prom/api/v1/query, POST /api/v1/ts/b/query -> full read AND write of DB 'b' (200 OK). The equivalent /api/v1/command/b correctly returns 403.

Fix: re-parent these handlers to DatabaseAbstractHandler, or add a shared resolveAuthorizedDatabase() choke point that enforces canAccessToDatabase and sets the engine principal before getDatabase(...). Fail closed when the security context is absent.